1. This question is about motion in a magnetic field.

An electron, that has been accelerated from rest by a potential difference of 250 V, enters a
region of magnetic field of strength 0.12 T that is directed into the plane of the page.

(a) The electron’s path while in the region of magnetic field is a quarter circle. Show that the

(i) speed of the electron after acceleration is 9.4 × 106 m s–1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) radius of the path is 4.5 × 10–4 m.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(b) The diagram below shows the momentum of the electron as it enters and leaves the region
of magnetic field. The magnitude of the initial momentum and of the final momentum is
8.6 × 10–24 N s.

IB Questionbank Physics 107

 (i) On the diagram above, draw an arrow to indicate the vector representing the
change in the momentum of the electron.
(1)

(ii) Show that the magnitude of the change in the momentum of the electron is
1.2 × 10–23 Ns.

...........................................................................................................................

...........................................................................................................................
(1)

(iii) The time the electron spends in the region of magnetic field is 7.4 × 10–11 s.
Estimate the magnitude of the average force on the electron.

...........................................................................................................................

...........................................................................................................................
(1)
(Total 7 marks)

2. This question is about forces.

An athlete trains by dragging a heavy load across a rough horizontal surface.

The athlete exerts a force of magnitude F on the load at an angle of 25° to the horizontal.

(a) Once the load is moving at a steady speed, the average horizontal frictional force acting
on the load is 470 N.

Calculate the average value of F that will enable the load to move at constant speed.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(b) The load is moved a horizontal distance of 2.5 km in 1.2 hours.

Calculate

(i) the work done on the load by the force F.

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Physics 108

 (ii) the minimum average power required to move the load.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(c) The athlete pulls the load uphill at the same speed as in part (a).

Explain, in terms of energy changes, why the minimum average power required is greater
than in (b)(ii).

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)
(Total 8 marks)

3. This question is about forces.

An athlete trains by dragging a heavy load across a rough horizontal surface.

The athlete exerts a force of magnitude F on the load at an angle of 25° to the horizontal.

(a) Once the load is moving at a steady speed, the average horizontal frictional force acting
on the load is 470 N.

Calculate the average value of F that will enable the load to move at constant speed.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(b) The load is moved a horizontal distance of 2.5 km in 1.2 hours.

Calculate

(i) the work done on the load by the force F.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Physics 109

 (ii) the minimum average power required to move the load.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(c) The athlete pulls the load uphill at the same speed as in part (a).

Explain, in terms of energy changes, why the minimum average power required is greater
than in (b)(ii).

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)
(Total 8 marks)

4. This question is about forces.

A solid iron ball of mass 770 kg is used on a building site. The ball is suspended by a rope from
a crane. The distance from the point of suspension to the centre of mass of the ball is 12 m.

(a) Calculate the tension in the rope when the ball hangs vertical and stationary.

......................................................................................................................................

......................................................................................................................................
(1)

(b) The ball is pulled back from the vertical and then released. It falls through a vertical
height of 1.6 m and strikes a wall.

(i) Calculate the speed of the ball just before impact.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Physics 110

 (ii) Calculate the tension in the rope just before impact.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(c) The ball is brought to rest in 0.15 s. The sketch graph below shows how the force the ball
exerts on the wall varies with time.

(i) State what quantity is represented by the area under the graph.

...........................................................................................................................
(1)

(ii) Determine the maximum force Fmax exerted by the ball on the wall.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)
(Total 10 marks)

IB Questionbank Physics 111

5. This question is about mechanics and thermal physics.

The graph shows the variation with time t of the speed v of a ball of mass 0.50 kg, that has been
released from rest above the Earth’s surface.

The force of air resistance is not negligible. Assume that the acceleration of free fall is
g = 9.81 m s–2.

(a) State, without any calculations, how the graph could be used to determine the distance
fallen.

......................................................................................................................................

......................................................................................................................................
(1)

(b) (i) In the space below, draw and label arrows to represent the forces on the ball at
2.0 s.

(1)

(ii) Use the graph opposite to show that the acceleration of the ball at 2.0 s is
approximately 4 m s–2.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Physics 112

 (iii) Calculate the magnitude of the force of air resistance on the ball at 2.0 s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(iv) State and explain whether the air resistance on the ball at t = 5.0 s is smaller than,
equal to or greater than the air resistance at t = 2.0 s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(c) After 10 s the ball has fallen 190 m.

(i) Show that the sum of the potential and kinetic energies of the ball has decreased by
780 J.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(ii) The specific heat capacity of the ball is 480 J kg–1 K–1. Estimate the increase in the
temperature of the ball.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(iii) State an assumption made in the estimate in (c)(ii).

...........................................................................................................................

...........................................................................................................................
(1)
(Total 14 marks)

6. This question is about mechanics and thermal physics.

IB Questionbank Physics 113

 The graph shows the variation with time t of the speed v of a ball of mass 0.50 kg, that has been
released from rest above the Earth’s surface.

The force of air resistance is not negligible. Assume that the acceleration of free fall is
g = 9.81 m s–2.

(a) State, without any calculations, how the graph could be used to determine the distance
fallen.

......................................................................................................................................

......................................................................................................................................
(1)

(b) (i) In the space below, draw and label arrows to represent the forces on the ball at
2.0 s.

(1)

(ii) Use the graph opposite to show that the acceleration of the ball at 2.0 s is
approximately 4 m s–2.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Physics 114

 (iii) Calculate the magnitude of the force of air resistance on the ball at 2.0 s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(iv) State and explain whether the air resistance on the ball at t = 5.0 s is smaller than,
equal to or greater than the air resistance at t = 2.0 s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(c) After 10 s the ball has fallen 190 m.

(i) Show that the sum of the potential and kinetic energies of the ball has decreased by
780 J.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(ii) The specific heat capacity of the ball is 480 J kg–1 K–1. Estimate the increase in the
temperature of the ball.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(iii) State an assumption made in the estimate in (c)(ii).

...........................................................................................................................

...........................................................................................................................
(1)
(Total 14 marks)

IB Questionbank Physics 115

7. This question is about power and efficiency.

A bus is travelling at a constant speed of 6.2 m s–1 along a section of road that is inclined at an
angle of 6.0° to the horizontal.

(a) (i) The bus is represented by the black dot shown below. Draw a labelled sketch to
represent the forces acting on the bus.

(4)

(ii) State the value of the rate of change of momentum of the bus.

...........................................................................................................................
(1)

(b) The total output power of the engine of the bus is 70 kW and the efficiency of the engine
is 35 %. Calculate the input power to the engine.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Physics 116

 (c) The mass of the bus is 8.5 × 103 kg. Determine the rate of increase of gravitational
potential energy of the bus.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(d) Using your answer to (c) and the data in (b), estimate the magnitude of the resistive forces
acting on the bus.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(e) The engine of the bus suddenly stops working.

(i) Determine the magnitude of the net force opposing the motion of the bus at the
instant at which the engine stops.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) Discuss, with reference to the air resistance, the change in the net force as the bus
slows down.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)
(Total 17 marks)

IB Questionbank Physics 117

8. This question is about power and efficiency.

A bus is travelling at a constant speed of 6.2 m s–1 along a section of road that is inclined at an
angle of 6.0° to the horizontal.

(a) (i) The bus is represented by the black dot shown below. Draw a labelled sketch to
represent the forces acting on the bus.

(4)

(ii) State the value of the rate of change of momentum of the bus.

...........................................................................................................................
(1)

(b) The total output power of the engine of the bus is 70 kW and the efficiency of the engine
is 35 %. Calculate the input power to the engine.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(c) The mass of the bus is 8.5 × 103 kg. Determine the rate of increase of gravitational
potential energy of the bus.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

IB Questionbank Physics 118

 (d) Using your answer to (c) and the data in (b), estimate the magnitude of the resistive forces
acting on the bus.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
(Total 13 marks)

9. This question is about kicking a football.

A ball is suspended from a ceiling by a string of length 7.5 m. The ball is kicked horizontally
and rises to a maximum height of 6.0 m.

(a) Assuming that the air resistance is negligible, show that the initial speed of the ball is
11 m s–1.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(b) The mass of the ball is 0.55 kg and the impact time of the kicker’s foot with the ball is
150 ms. Estimate the average force exerted on the ball by the kick.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(c) (i) Explain why the tension in the string increases immediately after the ball is kicked.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

IB Questionbank Physics 119

 (ii) Calculate the tension in the string immediately after the ball is kicked. Assume that
the string is vertical.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)
Total 10 marks)

10. This question is about momentum, energy and power.

(a) In his Principia Mathematica Newton expressed his third law of motion as “to every
action there is always opposed an equal reaction”. State what Newton meant by this law.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(1)

(b) A book is released from rest and falls towards the surface of Earth. Discuss how the
conservation of momentum applies to the Earth-book system.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(c) A large swinging ball is used to drive a horizontal iron spike into a vertical wall. The
centre of the ball falls through a vertical height of 1.6 m before striking the spike in the
position shown.

IB Questionbank Physics 120

 The mass of the ball is 3.5 kg and the mass of the spike is 0.80 kg. Immediately after
striking the spike, the ball and spike move together. Show that the

(i) speed of the ball on striking the spike is 5.6 m s–1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(1)

(ii) energy dissipated as a result of the collision is about 10 J.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(4)

(d) As a result of the ball striking the spike, the spike is driven a distance 7.3 × 10–2 m into
the wall. Calculate, assuming it to be constant, the friction force F between the spike and
wall.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(e) The machine that is used to raise the ball has a useful power output of 18 W. Calculate
how long it takes for the machine to raise the ball through a height of 1.6 m.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
(Total 15 marks)

IB Questionbank Physics 121

11. This question is about momentum, energy and power.

(a) In his Principia Mathematica Newton expressed his third law of motion as “to every
action there is always opposed an equal reaction”. State what Newton meant by this law.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(1)

(b) A book is released from rest and falls towards the surface of Earth. Discuss how the
conservation of momentum applies to the Earth-book system.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(c) A large swinging ball is used to drive a horizontal iron spike into a vertical wall.
The centre of the ball falls through a vertical height of 1.6 m before striking the spike in
the position shown.

The mass of the ball is 3.5 kg and the mass of the spike is 0.80 kg. Immediately after
striking the spike, the ball and spike move together. Show that the

(i) speed of the ball on striking the spike is 5.6 m s–1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(1)

IB Questionbank Physics 122

 (ii) energy dissipated as a result of the collision is about 10 J.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(4)

(d) As a result of the ball striking the spike, the spike is driven a distance 7.3 × 10–2 m into
the wall. Calculate, assuming it to be constant, the friction force F between the spike and
wall.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(e) The machine that is used to raise the ball has a useful power output of 18 W. Calculate
how long it takes for the machine to raise the ball through a height of 1.6 m.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
(Total 15 marks)

12. This question is about motion of a ball falling in oil.

(a) Distinguish between average speed and instantaneous speed.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Physics 123

 (b) A small steel ball of mass M is dropped from rest into a long vertical tube that contains
oil.

The sketch graph shows how the speed v of the ball varies with time t.

Explain how you would use the graph to find the average speed of the ball between t = 0
and t = t1.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(c) The gradient of the graph at t = t1 is k. Deduce an expression in terms of k, M and g, the
acceleration of free fall, for the magnitude of the frictional force F acting on the ball at t =
t1.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(d) State and explain the magnitude of the frictional force acting on the ball at t = t2.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
(Total 11 marks)

IB Questionbank Physics 124

13. This question is about dynamics and energy.

A bullet of mass 32 g is fired from a gun. The graph shows the variation of the force F on the
bullet with time t as it travels along the barrel of the gun.

The bullet is fired at time t = 0 and the length of the barrel is 0.70 m.

(a) State and explain why it is inappropriate to use the equation s = ut + 1

2
at 2 to calculate
the acceleration of the bullet.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

(b) Use the graph to

(i) determine the average acceleration of the bullet during the final 2.0 ms of the
graph.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

IB Questionbank Physics 125

 (ii) show that the change in momentum of the bullet, as the bullet travels along the
length of the barrel, is approximately 9 N s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(c) Use the answer in (b)(ii) to calculate the

(i) speed of the bullet as it leaves the barrel.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) average power delivered to the bullet.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(d) Use Newton’s third law to explain why a gun will recoil when a bullet is fired.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
(Total 15 marks)

IB Questionbank Physics 126

14. This question is about dynamics and energy.

A bullet of mass 32 g is fired from a gun. The graph shows the variation of the force F on the
bullet with time t as it travels along the barrel of the gun.

The bullet is fired at time t = 0 and the length of the barrel is 0.70 m.

1 2
(a) State and explain why it is inappropriate to use the equation s = ut + at to calculate
2
the acceleration of the bullet.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Physics 127

 (b) Use the graph to

(i) determine the average acceleration of the bullet during the final 2.0 ms of the
graph.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) show that the change in momentum of the bullet, as the bullet travels along the
length of the barrel, is approximately 9 N s.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(c) Use the answer in (b)(ii) to calculate the

(i) speed of the bullet as it leaves the barrel.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) average power delivered to the bullet.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

IB Questionbank Physics 128

 (d) Use Newton’s third law to explain why a gun will recoil when a bullet is fired.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)
(Total 15 marks)

15. This question is about a simple pendulum.

(a) A pendulum consists of a bob suspended by a light inextensible string from a rigid
support. The pendulum bob is moved to one side and then released. The sketch graph
shows how the displacement of the pendulum bob undergoing simple harmonic motion
varies with time over one time period.

On the sketch graph above,

(i) label with the letter A a point at which the acceleration of the pendulum bob is a
maximum.
(1)

(ii) label with the letter V a point at which the speed of the pendulum bob is a
maximum.
(1)

(b) Explain why the magnitude of the tension in the string at the midpoint of the oscillation is
greater than the weight of the pendulum bob.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

IB Questionbank Physics 129

 (c) The pendulum bob is moved to one side until its centre is 25 mm above its rest position
and then released.

(i) Show that the speed of the pendulum bob at the midpoint of the oscillation is
0.70 m s–1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) The mass of the pendulum bob is 0.057 kg. The centre of the pendulum bob is 0.80
m below the support. Calculate the magnitude of the tension in the string when the
pendulum bob is vertically below the point of suspension.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

(d) The point of suspension of the pendulum bob is moved from side to side with a small
amplitude and at a variable driving frequency f.

For each value of the driving frequency a steady

constant amplitude A is reached. The oscillations of
the pendulum bob are lightly damped.

IB Questionbank Physics 130

 (i) On the axes below, sketch a graph to show the variation of A with f.

(2)

(ii) Explain, with reference to the graph in (d)(i), what is meant by resonance.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(e) The pendulum bob is now immersed in water and the variable frequency driving force in
(d) is again applied. Suggest the effect this immersion of the pendulum bob will have on
the shape of your graph in (d)(i).

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)
(Total 16 marks)

16. This question is about collisions.

(a) State the principle of conservation of momentum.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)

IB Questionbank Physics 131

 (b) In an experiment, an air-rifle pellet is fired into a block of modelling clay that rests on a
table.

(not to scale)

The air-rifle pellet remains inside the clay block after the impact.

As a result of the collision, the clay block slides along the table in a straight line and
comes to rest. Further data relating to the experiment are given below.

Mass of air-rifle pellet = 2.0 g

Mass of clay block = 56 g
Velocity of impact of air-rifle pellet = 140 m s–1
Stopping distance of clay block = 2.8 m

(i) Show that the initial speed of the clay block after the air-rifle pellet strikes it is
4.8 m s–1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) Calculate the average frictional force that the surface of the table exerts on the clay
block whilst the clay block is moving.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(4)

IB Questionbank Physics 132

 (c) Discuss the energy transformations that occur in the clay block and the air-rifle pellet
from the moment the air-rifle pellet strikes the block until the clay block comes to rest.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(d) The clay block is dropped from rest from the edge of the table and falls vertically to the
ground. The table is 0.85 m above the ground. Calculate the speed with which the clay
block strikes the ground.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(2)
(Total 13 marks)

17. This question is about the simple pendulum.

(a) A pendulum consists of a bob suspended by a light inextensible string from a rigid
support. The pendulum bob is moved to one side and then released. The sketch graph
shows how the displacement of the pendulum bob undergoing simple harmonic motion
varies with time over one time period.

On the sketch graph above,

(i) label with the letter A a point at which the acceleration of the pendulum bob is a
maximum.
(1)

(ii) label with the letter V a point at which the speed of the pendulum bob is a
maximum.
(1)

IB Questionbank Physics 133

 (b) Explain why the magnitude of the tension in the string at the midpoint of the oscillation is
greater than the weight of the pendulum bob.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................
(3)

(c) The pendulum bob is moved to one side until its centre is 25 mm above its rest position
and then released.

(i) Show that the speed of the pendulum bob at the midpoint of the oscillation is
0.70 m s–1.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(2)

(ii) The mass of the pendulum bob is 0.057 kg. The centre of the pendulum bob is 0.80
m below the support. Calculate the magnitude of the tension in the string when the
pendulum bob is vertically below the point of suspension.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................
(3)

IB Questionbank Physics 134

 (d) The point of suspension of the pendulum bob is moved from side to side with a small
amplitude and at a variable driving frequency f.

For each value of the driving frequency a steady constant amplitude A is reached. The
oscillations of the pendulum bob are lightly damped.

(i) On the axes below, sketch a graph to show the variation of A with f.

(2)

(ii) Explain, with reference to the graph in (d)(i), what is meant by resonance.

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(2)

(e) The pendulum bob is now immersed in water and the variable frequency driving force in
(d) is again applied. Suggest the effect this immersion of the pendulum bob will have on
the shape of your graph in (d)(i).

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(2)
(Total 16 marks)

IB Questionbank Physics 135

18. This question is about collisions.

(a) State the principle of conservation of momentum.

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(b) In an experiment, an air-rifle pellet is fired into a block of modelling clay that rests on a
table.

(not to scale)

The air-rifle pellet remains inside the clay block after the impact.

As a result of the collision, the clay block slides along the table in a straight line and
comes to rest. Further data relating to the experiment are given below.

Mass of air-rifle pellet = 2.0 g

Mass of clay block = 56 g
Velocity of impact of air-rifle pellet = 140 m s–1
Stopping distance of clay block = 2.8 m

(i) Show that the initial speed of the clay block after the air-rifle pellet strikes it is
4.8 m s–1.

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(2)

IB Questionbank Physics 136

 (ii) Calculate the average frictional force that the surface of the table exerts on the clay
block whilst the clay block is moving.

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(4)

(c) The experiment is repeated with the clay block placed at the edge of the table so that it is
fired away from the table. The initial speed of the clay block is 4.3 m s–1 horizontally.
The table surface is 0.85 m above the ground.

(not to scale)

(i) Ignoring air resistance, calculate the horizontal distance travelled by the clay block
before it strikes the ground.

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(4)

(ii) The diagram in (c) shows the path of the clay block neglecting air resistance. On
the diagram, draw the approximate shape of the path that the clay block will take
assuming that air resistance acts on the clay block.
(3)
(Total 15 marks)

IB Questionbank Physics 137

19. This question is about force and energies.

(a) A system consists of a bicycle and cyclist travelling at a constant velocity along a
horizontal road.

(i) State the value of the net force acting on the cyclist.

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(1)

(ii) On the diagram draw labelled arrows to represent the vertical forces acting on the
bicycle.
(2)

(iii) With reference to the horizontal forces acting on the system, explain why the
system is travelling at constant velocity.

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(2)

(b) The total resistive force acting on the system is 40 N and its speed is 8.0 m s–1. Calculate
the useful power output of the cyclist.

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(1)

(c) The cyclist stops pedalling and the system comes to rest. The total mass of the system is
70 kg.

(i) Calculate the magnitude of the initial acceleration of the system.

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(2)

IB Questionbank Physics 138

 (ii) Estimate the distance taken by the system to come to rest from the time the cyclist
stops pedalling.

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(2)

(iii) State and explain one reason why your answer to (c)(ii) is only an estimate.

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(2)
(Total 12 marks)

IB Questionbank Physics 139