Work, Energy and Contact Number: 9667591930 /

Power 8527521718

1 A particle of mass m is attached to a string and is 5 When a body moves non-uniformly on a circular
moving in a vertical circle. Tension in the string when path:
the particle is at its highest and lowest point is T1 and T2 1. no work is done by the tangential force.
respectively. Here T2 − T1 is equal to: 2. no work is done by the centripetal force.
1. mg 2. 2mg 3. work done by the tangential force is always positive.
3. 4mg 4. 6mg 4. work done by the centripetal force is negative.

2 A body initially at rest and sliding along a

6 Consider a drop of rainwater having a mass of 1 gm
frictionless track from a height h (as shown in the falling from a height of 1 km. It hits the ground with a
figure) just completes a vertical circle of diameter speed of 50 m/s. Take g as constant with a value
AB = D. The height h is equal to: 2
10 m/s . The work done by the
(i) gravitational force and the
(ii) resistive force of air is:
1. (i) 1.25 J; (ii) − 8.25 J
2. (i) 100 J; (ii) 8.75 J
3. (i) 10 J; (ii) − 8.75 J
4. (i) − 10 J; (ii) − 8.75 J

3
7 A mass m is attached to a thin wire and whirled in a
1. 2 D vertical circle. The wire is most likely to break when:
2. D 1. inclined at an angle of 60∘ from vertical.
7
3. 4 D 2. the mass is at the highest point.
4. 54 D 3. the wire is horizontal.
4. the mass is at the lowest point.
3 Water falls from a height of 60 m at the rate of 15
kg/s to operate a turbine. The losses due to frictional 8 A body of mass 1 kg begins to move under the
force are 10% of the input energy. How much power is action of a time-dependent force F→ = (2t^i + 3t2 ^j)
generated by the turbine? (g = 10) m/s2
1. 12.3 kW 2. 7.0 kW N, where ^i and ^j are unit vectors along the X and Y-
axis. What power will be developed by the force at the
3. 10.2 kW 4. 8.1 kW
time (t)?
1. (2t2 + 4t4 ) W
4 A gravitational field is present in a region, and a
2. (2t3 + 3t3 ) W
mass is shifted from A to B through different paths as 3 5
shown. If W1 , W2 and W3 represent the work done by 3. (2t + 3t ) W
3 4
the gravitational force along their respective paths, then: 4. (2t + 3t ) W

1. W1 = W2 = W3 2. W1 > W2 > W3
3. W1 > W3 > W2 4. W1 < W2 < W3

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 Work, Energy and Contact Number: 9667591930 /
Power 8527521718

9 A stone is dropped from a height h. It hits the 14 A car of mass m starts from rest and accelerates so
ground with a certain momentum p. If the same stone is that the instantaneous power delivered to the car has a
dropped from a height 100% more than the previous constant magnitude P0 . The instantaneous velocity of
height, the momentum when it hits the ground will this car is proportional to:
1
change by: 1. t 2
1. 41% −1

2. 200% 2. t 2
3. 100% 3. t
√m
4. 68% 4. t2 P0

10 A moving block having mass m collides with 15 Given below are two statements:
another stationary block having a mass of 4m. The When a firecracker (rocket) explodes in
lighter block comes to rest after the collision. When the mid-air, its fragments fly in such a way
initial velocity of the lighter block is v, then the value of Assertion (A): that they continue moving in the same
the coefficient of restitution (e) will be: path, which the firecracker would have
1. 0.5 followed, had it not exploded.
2. 0.25 Explosion of cracker (rocket) occurs due
3. 0.8 Reason (R): to internal forces only and no external
4. 0.4 force acts for this explosion.
11 A particle with total energy E is moving in a
Both (A) and (R) are true and (R) is the correct
potential energy region U(x). The motion of the particle 1.
explanation of (A).
is restricted to the region where:
Both (A) and (R) are true but (R) is not the correct
1. U(x) < E 2.
explanation of (A).
2. U(x) = 0
3. (A) is true but (R) is false.
3. U(x) ≤ E
4. (A) is false but (R) is true.
4. U(x) > E
16 The potential energy of a particle in a force field is
12 A particle of mass m is driven by a machine that A B
delivers a constant power of k watts. If the particle starts U = r2 − r where A and B are positive constants and
from rest, the force on the particle at time t is: r is the distance of the particle from the center of the
1. √ 2 t
mk −1/2 field. For stable equilibrium, the distance of the particle
is:
√ −1/2
2. mkt 1. B
2. B
−1/2 A 2A
3. √2mkt 2A A
3. 4.
4. 12 √mkt−1/2 B B

13 Two identical balls A and B having velocities of

0.5 m/s and −0.3 m/s, respectively, collide elastically in
one dimension. The velocities of B and A after the
collision, respectively, will be:
1. −0.5 m/s and 0.3 m/s
2. 0.5 m/s and − 0.3 m/s
3. −0.3 m/s and 0.5 m/s
4. 0.3 m/s and 0.5 m/s

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 Work, Energy and Contact Number: 9667591930 /
Power 8527521718

17 The position-time (x-t) graph of a particle of mass 20 A block of mass m is being lowered by means of a
2 kg is shown in the figure. Total work done on the string attached to it. The system moves down with a
particle from t = 0 to t = 4 s is: constant velocity. Then:

1. Work done by gravity on the block is positive.

Work done by force, F (the force of the string) on the
2.
block is negative.
1. 8 J Work done by gravity is equal in magnitude to that
3.
2. 4 J done by the string.
3. 0 J 4. All of the above are true.
4. can't be determined
21 A particle of mass 'm' is moving in a horizontal
18 An electric lift with a maximum load of 2000 kg circle of radius 'r' under a centripetal force equal to –
(lift+passengers) is moving up with a constant speed of
K/r2, where K is a constant. The total energy of the
1.5 ms–1. The frictional force opposing the motion is particle will be:
3000 N. The minimum power delivered by the motor to K
1. 2r
the lift in watts is: K
2. − 2r
(Take g = 10 ms–2)
1. 23500 3. − Kr
2. 23000 4. K
r
3. 20000
4. 34500 22 The bob of a simple pendulum having length l, is
19 Two particles of masses m1 and m2 move with displaced from the mean position to an angular position
θ with respect to vertical. If it is released, then the
initial velocities u1 and u2 respectively. On collision, velocity of the bob at the lowest position will be:
one of the particles gets excited to a higher level, after 1. √2gl(1 − cos θ)
absorbing energy E. If the final velocities of particles
are v1 and v2 , then we must have: 2. √2gl(1 + cos θ)
1. m21 u1 + m22 u2 − E = m21 v1 + m22 v2 3. √2gl cos θ
1 4. √2gl
2. 2
m1 u21 + 12 m2 u22 = 1
2
m1 v21 + 12 m2 v22
1
3. 2
m1 u21 + 12 m2 u22 − E = 12 m1 v21 + 12 m2 v22 23 A person-1 stands on an elevator moving with
1
4. 2
m21 u21 + 12 m22 u22 + E = 12 m21 v21 + 12 m22 v22 an initial velocity of 'v' & upward acceleration 'a'.
Another person-2 of the same mass m as person-1 is
standing on the same elevator. The work done by the
lift on the person-1 as observed by person-2 in time 't' is:
1. m(g) + a(vt) + 12 at2
2. − mg(vt) + 12 at2
3. 0
4. ma(vt) + 12 at2

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 Work, Energy and Contact Number: 9667591930 /
Power 8527521718

24 When an object is shot from the bottom of a long, 27 The relationship between force and position is
∘
smooth inclined plane kept at an angle of 60 with shown in the given figure (in a one-dimensional case).
horizontal, it can travel a distance x1 along the plane. The work done by the force in displacing a body from
But when the inclination is decreased to 30∘ and the x = 1 cm to x = 5 cm is:
same object is shot with the same velocity, it can travel
x2 distance. Then x1 : x2 will be:
1. 1 : 2√3
2. 1 : √2
3. √2 : 1
4. 1 : √3

25 A ball is thrown vertically downwards from a height

of 20 m with an initial velocity vo. It collides with the
ground, loses 50% of its energy in a collision and
rebounds to the same height. The initial velocity vo is: 1. 20 ergs
(Take g = 10 ms-2) 2. 60 ergs
3. 70 ergs
1. 14 ms-1 4. 700 ergs
2. 20 ms-1
3. 28 ms-1 28 When a spring is subjected to 4 N force, its length is
4. 10 ms -1 a metre and if 5 N is applied, its length is b metre. If 9 N
is applied, its length will be:
26 A block of mass m is placed in an elevator 1. 4b – 3a
g 2. 5b – a
moving down with an acceleration 3 . The work done by
3. 5b – 4a
the normal reaction on the block as the elevator moves 4. 5b – 2a
down through a height h is:
−2 mgh
1. 3 29 A body of mass 'm' is released from the top of a
− mgh fixed rough inclined plane as shown in the figure. If the
2. 3
2 mgh frictional force has magnitude F, then the body will
3. 3
mgh
reach the bottom with a velocity: (L = √2h)
4. 3

1. √2gh 2. √ 2Fmh

3. √2gh + 2F h
m
4. √2gh − 2√2F h
m

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 Work, Energy and Contact Number: 9667591930 /
Power 8527521718

30 An object of mass 500 g initially at rest is acted 33 The potential energy of a particle varies
upon by a variable force whose x-component varies with with distance r as shown in the graph. The force acting
x in the manner shown. The velocities of the object at on the particle is equal to zero at:
the points x = 8 m and x = 12 m would have the
respective values of nearly:

1. P
2. S
3. both Q and R
4. both P and S

34 A bullet from a gun is fired on a rectangular wooden

1. 18 m/s and 22.4 m/s 2. 23 m/s and 22.4 m/s block with velocity u. When bullet travels 24 cm
through the block along its length horizontally, velocity
3. 23 m/s and 20.6 m/s 4. 18 m/s and 20.6 m/s of bullet becomes u/3. Then it further penetrates into the
block in the same direction before coming to rest exactly
31 A uniform chain of length L and mass M is lying at the other end of the block. The total length of the
on a smooth table and one-third of its length is hanging block is:
vertically down over the edge of the table. If g is 1. 30 cm
acceleration due to gravity, the work required to pull the2. 27 cm
hanging part on the table is: 3. 24 cm
1. MgL 4. 28 cm
2. MgL/3
3. MgL/9 35 The potential energy of a 1 kg particle free to move
4. MgL/18 along the x-axis is given by:
U(x) = ( x4 − )J
4 x2
32 A bullet of mass m hits a stationary block of mass 2

M elastically. The transfer of energy is the maximum, The total mechanical energy of the particle is 2J. Then,
when: the maximum speed (in ms-1) will be
1. M = m 1. 3
√2
2. M = 2m
2. √2
3. M ≪ m
4. M ≫ m 3. 1
√2
4. 2

36 A bullet of mass 10 g moving horizontal with a

velocity of 400 m/s strikes a wood block of mass 2 kg
which is suspended by light inextensible string of length
5 m. As a result, the centre of gravity of the block is
found to rise a vertical distance of 10 cm. The speed of
the bullet after it emerges horizontally from the block
will be:
1. 100 m/s 2. 80 m/s
3. 120 m/s 4. 160 m/s

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 Work, Energy and Contact Number: 9667591930 /
Power 8527521718

37 A particle of mass 'm' is projected at an angle 'α'

with the horizontal, with an initial velocity 'u'. The work Fill OMR Sheet*
done by gravity during the time it reaches its highest
point is: *If above link doesn't work, please go to test link from
2
1. u sin a2 where you got the pdf and fill OMR from there. After
mu2 cos2 α filling the OMR, you would get answers and explanations
2. 2 for the questions in the test.
mu2 sin2 α
3. 2
mu2 sin2 α
4. − 2

38 A weight 'mg' is suspended from a spring. CLICK HERE to get

The energy stored in the spring is U. The elongation in
the spring is:
2U
FREE ACCESS for 2
1. mg
2. U
mg
days of ANY
3.
√2U
mg
NEETprep course
U
4.
√2 mg

39 On a frictionless surface, a block of mass M

moving at speed v collides elastically with another block
of the same mass M which is initially at rest. After the
collision, the first block moves at an angle θ to its initial
direction and has a speed 3v . The second block’s speed
after the collision will be:
2√2 3
1. v 2. 4
v
3
3 √3
3. v 4. v
√2 2

40 The kinetic energy of a body is increased by

21%. The percentage increase in the magnitude of linear
momentum of the body will be:
1. 10%
2. 20%
3. Zero
4. 11.5%

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