Triple Science

5 Forces
Higher Questions & Answers
Q1.
Forces have different effects.

(a) (i) Use the correct answer from the box to complete the sentence.

slowing stretching turning

The moment of a force is the ________________________________ effect of

the force.
(1)

(ii) What is meant by the centre of mass of an object?

______________________________________________________________

______________________________________________________________
(1)

(b) Some children build a see-saw using a plank of wood and a pivot.
The centre of mass of the plank is above the pivot.

Figure 1 shows a boy sitting on the see-saw. His weight is 400 N.

Figure 1

Calculate the anticlockwise moment of the boy in Nm.

___________________________________________________________________

___________________________________________________________________

Anticlockwise moment = ____________________ Nm

(2)

(c) Figure 2 shows a girl sitting at the opposite end of the see-saw. Her weight is 300
N.

Figure 2
The see-saw is now balanced.

The children move the plank. Its centre of mass, M, is now 0.25 m from the pivot as
shown in Figure 3.

Figure 3

The boy and girl sit on the see-saw as shown in Figure 3.

(i) Describe and explain the rotation of the see-saw.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(3)

(ii) The boy gets off the see-saw and a bigger boy gets on it in the same place.
The girl stays in the position shown in Figure 3. The plank is balanced. The
weight of the plank is 270 N.

Calculate the weight of the bigger boy.

______________________________________________________________

______________________________________________________________

______________________________________________________________
 ______________________________________________________________

______________________________________________________________

______________________________________________________________

Weight of the bigger boy = ____________________ N

(3)
(Total 10 marks)

Q2.
A paintball gun is used to fire a small ball of paint, called a paintball, at a target.

The figure below shows someone just about to fire a paintball gun.

The paintball is inside the gun.

(a) What is the momentum of the paintball before the gun is fired?

___________________________________________________________________

Give a reason for your answer.

___________________________________________________________________

___________________________________________________________________
(2)

(b) The gun fires the paintball forwards at a velocity of 90 m / s.

The paintball has a mass of 0.0030 kg.

Calculate the momentum of the paintball just after the gun is fired.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Momentum = ____________________ kg m / s
(2)

(c) The momentum of the gun and paintball is conserved.

 Use the correct answer from the box to complete the sentence.

equal to greater than less than

The total momentum of the gun and paintball just after the gun is fired

will be ____________________________ the total momentum of the gun and

paintball before the gun is fired.

(1)
(Total 5 marks)

Q3.
The diagram shows a man standing in an airport queue with his wheeled bag.

(a) The man applies an upward force to the handle of his bag to stop the bag from
falling.
The moment of this force about the pivot is 36 Nm.

Calculate the upward force the man applies to the handle of his bag.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Force = ______________________________ N
(2)
 (b) When the man lets go of the bag handle, the bag falls and hits the floor.

Explain why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)
(Total 4 marks)

Q4.
Quantities in physics are either scalars or vectors.

(a) Use the correct answers from the box to complete the sentence.

acceleration direction distance speed time

Velocity is __________________________ in a given ________________ .

(2)

(b) Complete the table to show which quantities are scalars and which quantities are
vectors.

Put one tick ( ) in each row.

The first row has been completed for you.

Quantity Scalar Vector

Momentum

Acceleration

Distance

Force

Time

(3)

(c) The diagram shows two supermarket trolleys moving in the same direction.

Trolley A is full of shopping, has a total mass of 8 kg and is moving at a velocity of 2

m / s with a kinetic energy of 16 J.

Trolley B is empty, has a mass of 4 kg and is moving at a velocity of 0.5 m / s with a

kinetic energy of 0.5 J.

(i) Calculate the momentum of both trolley A and trolley B.

Give the unit.

______________________________________________________________

______________________________________________________________

Momentum of trolley A = _______________

Momentum of trolley B = _______________

Unit __________
(4)

(ii) The trolleys in the diagram collide and join together. They move off together.

Calculate the velocity with which they move off together.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

Velocity = _______________ m / s
(3)

(iii) In a different situation, the trolleys in the digram move at the same speeds as
before but now move towards each other.

Calculate the total momentum and the total kinetic energy of the two trolleys
before they collide.

______________________________________________________________

______________________________________________________________

Total momentum = _________________

______________________________________________________________

______________________________________________________________
 Total kinetic energy = _______________ J
(2)
(Total 14 marks)

Q5.
Before a new bus can be used on the roads, it must pass a stability test.
Figure 1 shows how the bus is tested.

(a) (i) The bus will topple over if the ramp is tilted at too great an angle.

Explain why.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(ii) The bus is tested to angles of tilt far greater than it would experience in normal
use.

Suggest two reasons why.

1. ____________________________________________________________

______________________________________________________________

2. ____________________________________________________________

______________________________________________________________
(2)
 (b) Figure 2 shows the hydraulic machine that is used to make the ramp tilt.

The pressure applied to the hydraulic liquid at the master piston is the same as the
pressure applied by the hydraulic liquid to the slave piston.

(i) State the property of the liquid that keeps the pressure at both pistons the
same.

______________________________________________________________
(1)

(ii) A 360 N force acts on the master piston.

Use information from Figure 2 to calculate the force applied by the hydraulic
liquid to the slave piston.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

Force = ___________________ N
(3)
(Total 8 marks)

Q6.
A train travels from town A to town B.

Figure 1 shows the route taken by the train.

Figure 1 has been drawn to scale.

Figure 1
(a) The distance the train travels between A and B is not the same as the displacement
of the train.

What is the difference between distance and displacement?

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(1)

(b) Use Figure 1 to determine the displacement of the train in travelling from A to B.

Show how you obtain your answer.

___________________________________________________________________

___________________________________________________________________

Displacement = ___________________ km

Direction = _________________________
(2)

(c) There are places on the journey where the train accelerates without changing
speed.

Explain how this can happen.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(d) Figure 2 shows how the velocity of the train changes with time as the train travels
along a straight section of the journey.
 Figure 2

Estimate the distance travelled by the train along the section of the journey shown in
Figure 2.

To gain full marks you must show how you worked out your answer.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Distance = _________________________ m
(3)
(Total 8 marks)

Q7.
The diagram below shows a person using a device called a jetpack. Water is forced
downwards from the jetpack and produces an upward force on the person.
 (a) State the condition necessary for the person to be able to remain stationary in mid-
air.

___________________________________________________________________

___________________________________________________________________
(1)

(b) The person weighs 700 N and the jetpack weighs 140 N.

(i) Calculate the combined mass of the person and the jetpack.

Gravitational field strength = 10 N/kg

______________________________________________________________

______________________________________________________________

______________________________________________________________

Combined mass = ___________ kg

(2)

(ii) Increasing the upward force to 1850 N causes the person to accelerate
upwards.

Calculate the acceleration of the person and the jetpack. Give the unit.

______________________________________________________________

______________________________________________________________

______________________________________________________________

______________________________________________________________

Acceleration = ___________ Unit ___________

(3)
(Total 6 marks)

Q8.
Figure 1 shows an exercise device called a chest expander. The three springs are
identical.

Figure 1

A person pulls outwards on the handles and does work to stretch the springs.

(a) Complete the following sentence.

When the springs are stretched ___________ ___________ energy is stored in the
springs.
(1)

(b) Figure 2 shows how the extension of a single spring from the chest expander
depends on the force acting on the spring.

Figure 2

(i) How can you tell, from Figure 2, that the limit of proportionality of the spring
has not been exceeded?

______________________________________________________________

______________________________________________________________
(1)

(ii) Use data from Figure 2 to calculate the spring constant of the spring.
Give the unit.

______________________________________________________________

______________________________________________________________
 ______________________________________________________________

Spring constant = ___________ Unit ___________

(3)

(iii) Three identical resistors joined in parallel in an electrical circuit share the total
current in the circuit.

In a similar way, the three springs in the chest expander share the total force
exerted.

By considering this similarity, use Figure 2 to determine the total force exerted
on the chest expander when each spring is stretched by 0.25 m.

______________________________________________________________

______________________________________________________________

Total force = ___________ N

(2)

(c) The student in Figure 3 is doing an exercise called a chin-up.

Figure 3

Each time the student does one chin-up he lifts his body 0.40 m vertically upwards.
The mass of the student is 65 kg.
The student is able to do 12 chin-ups in 60 seconds.

Calculate the power developed by the student.

Gravitational field strength = 10 N/kg

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Power = ___________ W
 (3)
(Total 10 marks)

Q9.
In 2011, some of the scientists working at the CERN particle laboratory published the
results of experiments they had conducted over the previous three years.

The scientists said that the results had shown that a particle, called a neutrino, was able
to travel faster than the speed of light.

These unexpected results challenged the physics theory that nothing can travel faster
than the speed of light.

(a) Suggest why most other scientists thought that the experimental results were
unbelievable.

___________________________________________________________________

___________________________________________________________________
(1)

(b) The scientists at CERN believed their results were correct but could not explain
them.

Suggest two reasons why the scientists decided to publish their results.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________
(2)

(c) The experiments conducted by the scientists involved measuring the time it took
neutrinos to travel from CERN to another laboratory 730 000 m away.

Using the data, the speed of the neutrinos was calculated to be 300 007 400 m / s.

Calculate the time it would take the neutrinos to travel 730 000 m at a speed of 300
007 400 m / s.

Give your answer in standard form.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Time = _____________________ s
(3)
 (d) In 2012, the scientists found that the unexpected results were caused by a timing
error.

The error meant that the time recorded was always 60 nanoseconds less than the
actual time.

Which one of the following is the same as 60 nanoseconds?

Tick one box.

60 × 10−3 s

60 × 10−6 s

60 × 10−9 s

(1)

(e) What name is given to the type of error made by the scientists?

___________________________________________________________________
(1)

(f) Suggest what the scientists should do to calculate an accurate value for the speed of
a neutrino.

___________________________________________________________________

___________________________________________________________________
(1)
(Total 9 marks)

Q10.
Figure 1 shows how atmospheric pressure varies with altitude.

Figure 1
(a) Explain why atmospheric pressure decreases with increasing altitude.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(3)

(b) When flying, the pressure inside the cabin of an aircraft is kept at 70 kPa.

The aircraft window has an area of 810 cm2.

Use data from Figure 1 to calculate the resultant force acting on an aircraft window
when the aircraft is flying at an altitude of 12 km.

Give your answer to two significant figures

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Resultant force = ___________________ N

 (5)

(c) Figure 2 shows the cross-section of one type of aircraft window.

Figure 2

Explain why the window has been designed to have this shape.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)
(Total 10 marks)

Q11.
The stopping distance of a car is the sum of the thinking distance and the braking
distance.

The table below shows how the thinking distance and braking distance vary with speed.

Thinking Braking
Speed
distance distance
in m / s
in m in m

10 6 6.0

15 9 13.5

20 12 24.0

25 15 37.5

30 18 54.0

(a) What is meant by the braking distance of a vehicle?

___________________________________________________________________

___________________________________________________________________
 (1)

(b) The data in the table above refers to a car in good mechanical condition driven by
an alert driver.

Explain why the stopping distance of the car increases if the driver is very tired.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(c) A student looks at the data in the table above and writes the following:

thinking distance ∝ speed

thinking distance ∝ speed

Explain whether the student is correct.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(d) Applying the brakes with too much force can cause a car to skid.

The distance a car skids before stopping depends on the friction between the road
surface and the car tyres and also the speed of the car.

Friction can be investigated by pulling a device called a ‘sled’ across a surface at

constant speed.

The figure below shows a sled being pulled correctly and incorrectly across a
surface.

The constant of friction for the surface is calculated from the value of the force
pulling the sled and the weight of the sled.

Why is it important that the sled is pulled at a constant speed?

Tick one box.

 If the sled accelerates it will be difficult to control.

If the sled accelerates the value for the constant

of friction will be wrong.

If the sled accelerates the normal contact force

will change.
(1)

(e) If the sled is pulled at an angle to the surface the value calculated for the constant of
friction would not be appropriate.

Explain why.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(2)

(f) By measuring the length of the skid marks, an accident investigator determines that
the distance a car travelled between the brakes being applied and stopping was 22
m.

The investigator used a sled to determine the friction. The investigator then
calculated that the car decelerated at 7.2 m / s2.

Calculate the speed of the car just before the brakes were applied.

Give your answer to two significant figures.

Use the correct equation from the Physics Equation Sheet.

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

___________________________________________________________________

Speed = __________________________ m / s
(3)
(Total 11 marks)
Mark schemes

Q1.
(a) (i) turning
accept turning ringed in the box
1

(ii) point at which mass (or weight) may be thought to be concentrated

accept the point from which the weight appears to act
allow focused for concentrated
do not accept most / some of the mass
do not accept region / area for point
1

(b) 600 (Nm)

400 × 1.5 gains 1 mark provided no subsequent steps shown
2

(c) (i) plank rotates clockwise

accept girl moves downwards
do not accept rotates to the right
1

(total) CM > (total) ACM

accept moment is larger on the girl’s side
1

weight of see-saw provides CM

answer must be in terms of moment
maximum of 2 marks if there is no reference to the weight of
the see-saw
1

(ii) W = 445 (N)

W × 1.5 = (270 × 0.25) + (300 × 2.0) gains 2 marks
allow for 1 mark:
total CM = total ACM either stated or implied
or
(270 × 0.25) + (300 × 2.0)
if no other marks given
3
[10]

Q2.
(a) Zero / 0
Accept none
Nothing is insufficent
1

velocity / speed = 0
 accept it is not moving
paintball has not been fired is insufficient
1

(b) 0.27
allow 1 mark for correct substitution, ie p = 0.003(0) × 90
provided no subsequent step
2

(c) equal to
1
[5]

Q3.
(a) 60
allow 1 mark for correct substitution (with d in metres),
ie 36 = F × 0.6
an answer of 0.6 or 6 gains 1 mark
2

(b) the line of action of the weight lies outside the base / bottom (of the bag)
accept line of action of the weight acts through the side
accept the weight (of the bag) acts outside the base / bottom
(of the bag)
1

a resultant / overall / unbalanced moment acts (on the bag)

accept the bag is not in equilibrium
do not accept the bag is unbalanced
1
[4]

Q4.
(a) speed
must be in correct order
1

direction
1

(b)
Quantity Scalar Vector

Momentum

Acceleration

Distance

Force

Time
 any three correct scores 2 marks
any two correct scores 1 mark
only one correct scores zero
3

(c) (i) 16 and 2

16 or 2 scores 2 marks
allow 1 mark for correct substitution, ie
8×2
or
4 × 0.5
3

kg m / s or N s
1

(ii) 1.5 (m / s)
or
their pA + pB = 12 × v correctly calculated
allow 2 marks for correct substitution, ie
18 = 12 × v
or
their pA + pB = 12 × v
18 or their pA + pB scores 1 mark if no other mark awarded
3

(iii) 14 (kg m / s)
or
their pA - pB
1

16.5 (J)
1
[14]

Q5.
(a) (i) the line of action of the weight (of the bus) lies / acts outside of the base (of
the bus)
allow line of action through the centre of mass lies / acts
outside the base
1

there is a resultant moment (acting on the bus)

1

(ii) in normal use the centre of mass may be in a different position

1
or
passengers on the bus may affect the position of the centre of mass

for safety, buses should always be tested beyond the normal operating
conditions / parameters
for safety is insufficient
accept in case something unexpected happens
 1

(b) (i) a liquid is (virtually) incompressible

accept a liquid cannot be squashed
a liquid is difficult to compress is insufficient
1

(ii) 84000
award 2 marks for

or

or award 1 mark for

or
300 000 (Pa)
seen anywhere
3
[8]

Q6.
(a) distance is a scalar and displacement is a vector

or

distance has magnitude only, displacement has magnitude and direction

1

(b) 37.5 km
accept any value between 37.0 and 38.0 inclusive
1

062° or N62°E
accept 62° to the right of the vertical
1
accept an angle in the range 60° −64°
accept the angle correctly measured and marked on the
diagram

(c) train changes direction so velocity changes

1

acceleration is the rate of change of velocity

1

(d) number of squares below line = 17

accept any number between 16 and 18 inclusive
1
 each square represents 500 m
1

distance = number of squares × value of each square correctly calculated − 8500 m

1
[8]

Q7.
(a) resultant force = zero
or
upward force = downward force
accept forces are balanced
accept weight for downward force
1

(b) (i) 84
allow 1 mark for correct substitution ie 840 = m × 10
2

(ii) 12
accept 12.02 for both marks
or
1010 ÷ their (b)(i) correctly calculated
a resultant force of 1010 (N) gains 1 mark
an answer 22(.02) gains 1 mark
2

m/s2
accept m/s/s
1
[6]

Q8.
(a) elastic potential
1

(b) (i) line is straight

accept line does not curve
1

(ii) 400
allow 1 mark for correct substitution of any pair of numbers
correctly taken from the graph e.g.160 = k × 0.40
2

newtons per metre or N/m

if symbols are used they must be correct
1

(iii) 300
allow 1 mark for correctly obtaining force on 1 spring = 100N
2

(c) 52
 allow 2 marks for calculating change in gpe for 1 chin-up as
260 (J) or for 12 chin-ups as 3120 (J)
an answer 4.3 gains 2 marks
allow 1 mark for correct substitution into gpe equation ie gpe
= 65 × 10 × 0.4 (× 12)
or
correct use of power equation with an incorrect value for
energy transferred
3
[10]

Q9.
(a) any sensible suggestion eg

• theory supported by results from other experiments

• could not believe the ‘theory’ could be wrong
• ‘theory’ is the basis of many other ideas
1

(b) any two from:

• to allow peer review of data

• to assess the reproducibility of the data
• to promote further enquiry / experiments
• to encourage other scientists to develop explanations / new theories
2

(c) 730 000 = 300 007 400 × time

1

time =
this step without the previous step stated gains 2 marks
1

2.43(3273) × 10−3 s
accept 0.00243(3273) s
1
allow 2.43(3273) × 10 with no working for 4 marks
−3

(d) 60 × 10−9 s
1

(e) systematic error

1

(f) add on 60 nanoseconds to each time recorded (then recalculate)

1
[9]

Q10.
(a) air molecules colliding with a surface create pressure
1
 at increasing altitude distance between molecules increases

or

at increasing altitude fewer molecules (above a surface)

1

so number of collisions with a surface decreases

or

or so always less weight of air than below (the surface)

1

(b) atmospheric pressure = 20 kPa from graph and conversion of 810 cm2 to 0.081 m2
allow ecf for an incorrect value clearly obtained from the
graph
1

5 × 104 = F

0.081
1

F = 5 × 104 × 0.081
1

4050
1

4100 (N)
1
allow 4100 (N) with no working shown for 5 marks
allow 4050 with no working shown for 4 marks

(c) force from air pressure acting from inside to outside bigger than force acting inwards
1

so keeps the window in position

1
[10]

Q11.
(a) the distance travelled under the braking force
1

(b) the reaction time will increase

1

increasing the thinking distance (and so increasing stopping distance)

(increases stopping distance is insufficient)
1

(c) No, because although when the speed increases the thinking distance increases by
the same factor the braking distance does not.
1

eg
 increasing from 10 m / s to 20 m / s increases thinking distance from 6 m to 12 m
but the braking distance increases from 6 m to 24 m
1

(d) If the sled accelerates the value for the constant of friction will be wrong.
1

(e) only a (the horizontal) component of the force would be pulling the sled forward
1

the vertical component of the force (effectively) lifts the sled reducing the force of the
surface on the sled
1

(f) − u2 = 2 × −7.2 × 22
award this mark even with 02 and / or the negative sign
missing
1

u = 17.7(99)
1

18
1
allow 18 with no working shown for 3 marks
allow 17.7(99) then incorrectly rounded to 17 for 2 marks
[11]