NEET : CHAPTER WISE TEST-6

SUBJECT :- PHYSICS DATE.............................................................

th
CLASS :- 11 NAME............................................................
CHAPTER :- WORK,POWER,ENERGY SECTION......................................................
(SECTION-A)
1. A body of mass m is moving in a circle of 5. A particle is acted upon by a force of
radius r with a constant speed v. The force constant magnitude which is always
mv 2 perpendicular to the velocity of the
on the body is and is directed
r particle, the motion of the particle takes
towards the centre. What is the work done place in a plane. It follows that
by this force in moving the body over half (A) Its velocity is constant
the circumference of the circle
(B) Its acceleration is constant
mv 2
(A) (B) Zero (C) Its kinetic energy is constant
r 2
(D) It moves in a straight line
mv 2 r 2
(C) (D)
r2 mv 2 6. A particle moves under the effect of a
force F = Cx from x = 0 to x  x 1 . The
2. A force acts on a 30 gm particle in such a
way that the position of the particle as a work done in the process is
1
function of time is given by x  3 t  4 t 2  t 3 , (A) Cx 12 (B) Cx 12
2
where x is in metres and t is in seconds.
The work done during the first 4 seconds (C) Cx 1 (D) Zero
is
(A) 5.28 J (B) 450 Mj 7. The potential energy of a certain spring
(C) 490 mJ (D) 530 mJ
when stretched through a distance ‘S’ is
3. A particle is dropped from a height h. A 10 joule. The amount of work (in joule) that
constant horizontal velocity is given to the must be done on this spring to stretch it
particle. Taking g to be constant every through an additional distance ‘S’ will be
where, kinetic energy E of the particle with (A) 30 (B) 40 (C) 10 (D) 20
respect to time t is correctly shown in
8. The spring extends by x on loading, then
energy stored by the spring is :
(A)
(if T is the tension in spring and k is spring
constant)
T2 T2
(A) (B)
2k 2k 2
(B) 2k 2T 2
(C) 2
(D)
T k

9. The potential energy between two atoms

a b
in a molecule is given by U(x )   ;
x 12 x 6
(C)
where a and b are positive constants and
x is the distance between the atoms. The
atom is in stable equilibrium when
11 a a
(A) x  6 (B) x  6
5b 2b
(D)
2a
(C) x  0 (D) x  6
b

 10. A light and a heavy body have equal

4. A force (F)  3ˆi  cˆj  2kˆ acting on a particle
 momenta. Which one has greater K.E
causes a displacement: (s )  4ˆi  2ˆj  3kˆ in (A) The light body
its own direction. If the work done is 6 J , (B) The heavy body
then the value of 'c' is (C) The K.E. are equal
(A) 0 (B) 1 (C) 6 (D) 12 (D) Data is incomplete

PG #1
11. A body of mass 2 kg is thrown up vertically 17. A bomb of mass 9kg explodes into 2
with K.E. of 490 joules. If the acceleration pieces of mass 3kg and 6kg. The velocity
due to gravity is 9.8 m / s 2 , then the height of mass 3kg is 1.6 m/s, the K.E. of mass
at which the K.E. of the body becomes half 6kg is.
its original value is given by (A) 3.84 J (B) 9.6 J
(A) 50 m (B) 12.5 m (C) 1.92 J (D) 2.92 J
(C) 25 m (D) 10 m
18. A bomb of mass 3.0 Kg explodes in air
12. If the K.E. of a body is increased by 300%, into two pieces of masses 2.0 kg and 1.0
its momentum will increase by kg. The smaller mass goes at a speed of
(A) 100% (B) 150% 80 m/s.The total energy imparted to the
(C) 300 % (D) 175% two fragments is.
(A) 1.07 kJ (B) 2.14 kJ
(C) 2.4 kJ (D) 4.8 kJ
13. A light and a heavy body have equal kinetic
energy. Which one has a greater
19. A block of mass m initially at rest is
momentum ?
dropped from a height h on to a spring of
(A) The light body
force constant k. the maximum
(B) The heavy body
compression in the spring is x then.
(C) Both have equal momentum
(D) It is not possible to say anything
without additional information h

14. A 4 kg mass and a 1 kg mass are moving

with equal kinetic energies. The ratio of
the magnitudes of their linear momenta is
(A) 1 : 2 (B) 1 : 1
(C) 2 : 1 (D) 4 : 1

15. A block of mass m is attached to two

unstretched springs of spring constants k 1 1 2
(A) mgh  kx
2
and k2 as shown in figure. The block is
1
displaced towards right through a distance (B) mg (h  x )  kx 2
2
x and is released. Find the speed of the 1
block as it passes through the mean (C) mgh  k (x  h) 2
2
position shown.
1
(D) mg (h  x )  k (x  h) 2
2

20. A body of mass m accelerates uniformly

from rest to v1 in time t1 . As a function of
k1  k 2 k1k 2
(A) x (B) x time t, the instantaneous power delivered
m m(k1  k 2 ) to the body is.
mv 1 t mv 12 t
k12k 22 k13k 32 (A) (B)
(C) x (D) t1 t1
m(k12  k 22 ) m(k13  k 32 )
mv 1 t 2 mv 12 t
(C) (D)
t1 t 12
16. What is the velocity of the bob of a simple
pendulum at its mean position, if it is able 21. A weight lifter lifts 300 kg from the ground
to rise to vertical height of 10 cm (Take to a height of 2 meter in 3 second. The
g  9 .8 m / s 2 ) average power generated by him is
(A) 5880 watt (B) 4410 watt
(C) 2205 watt (D) 1960 watt

22. A 60 kg man runs up a staircase in 12

seconds while a 50 kg man runs up the
same staircase in 11, seconds, the ratio of
the rate of doing their work is
(A) 0.6 m/s (B) 1.4 m/s (A) 6 : 5 (B) 12 : 11
(C) 1.8 m/s (D) 2.2 m/s (C) 11 : 10 (D) 10 : 11

PG #2
23. A force of 2ˆi  3ˆj  4 kˆ N acts on a body for 28. A particle moves under the influence of a
force F = kx in one dimensions (k is a
4 second, produces a displacement of
positive constant and x is the distance of
(3ˆi  4 ˆj  5 kˆ )m . The power used is the particle from the origin). Assume that
(A) 9.5 W (B) 7.5 W the potential energy of the particle at the
(C) 6.5 W (D) 4.5 W origin is zero, the schematic diagram of
the potential energy U as a function of x is
24. A wedge of mass M fitted with a spring of given by
stiffness ‘k’ is kept on a smooth horizontal
surface. A rod of mass m is kept on the
wedge as shown in the figure. System is in (A)
equilibrium. Assuming that all surfaces are
smooth, the potential energy stored in the
spring is :

(B)

mg2 tan2  m2 gtan2 

(A) (B)
2K 2K
m2g2 tan2  m2g2 tan2  (C)
(C) (D)
2K K

25. A car of mass ‘m’ is driven with

acceleration ‘a’ along a straight level road
against a constant external resistive force (D)
‘R’. When the velocity of the car is ‘V’, the
rate at which the engine of the car is doing
work will be
(A) RV (B) maV 29. Which of the following statements is true
(C) (R + ma)V (D) (ma – R)V (A) In elastic collisions, the momentum is
conserved but not in inelastic collisions
(B) Both kinetic energy and momentum
26. A particle of mass m moving with are conserved in elastic as well as
horizontal speed 6 m/sec as shown in inelastic collisions
figure. If m  M then for one dimensional (C) Total kinetic energy is not conserved
elastic collision, the speed of lighter but momentum is conserved in inelastic
particle after collision will be collisions
(D) Total kinetic energy is conserved in
u1 = 6 m/s u2 = 4 m/s
elastic collisions but momentum is not
m M conserved in elastic collisions

(A) 2m/sec in original direction 30. A mass 'm' moves with a velocity 'v' and
collides inelastically with another identical
(B) 2 m/sec opposite to the original
mass. After collision the Ist mass moves
direction
v
(C) 4 m/sec opposite to the original with velocity in a direction
3
direction
perpendicular to the initial direction of
(D) 4 m/sec in original direction nd
motion. Find the speed of the 2 mass
after collision
27. A steel ball of radius 2 cm is at rest on a v
frictionless surface. Another ball of radius
3
4cm moving at a velocity of 81 cm/sec v At rest
m m
collides elastically with first ball. After
before collision After collision
collision the smaller ball moves with speed
of 2 v
(A) v (B)
(A) 81 cm/sec (B) 63 cm/sec 3 3
(C) 144 cm/sec (D) None of these (C) v (D) 3v

PG #3
31. A bullet hits and gets embedded in a solid (SECTION-B)
block resting on a horizontal frictionless 36. Assertion : The rate of change of total
momentum of a many particle system is
table. What is conserved ? proportional to the sum of the internal
(A) Momentum and kinetic energy forces of the system.
Reason : Internal forces can change the
(B) Kinetic energy alone kinetic energy but not the momentum of
(C) Momentum alone the system.
(A) If both assertion and reason are true
(D) Neither momentum nor kinetic energy
and the reason is the correct explanation
of the assertion.
32. A moving body of mass m and velocity 3 (B) If both assertion and reason are true
km/h collides with a rest body of mass 2m but reason is not the correct explanation of
the assertion.
and sticks to it. Now the combined mass (C) If assertion is true but reason is false.
starts to move. What will be the combined (D) Both assertion and reason are false

velocity 37. A body of mass 6kg is under a force which

(A) 3 km/h (B) 2 km/h t2
causes displacement in it given by S 
(C) 1 km/h (D) 4 km/h 4
metres where t is time. The work done by
33. A metal ball of mass 2 kg moving with a the force in 2 seconds is
(A) 12 J (B) 9 J
velocity of 36 km/h has an head on (C) 6 J (D) 3 J
collision with a stationary ball of mass 3
kg. If after the collision, the two balls move 38. If W 1, W 2 and W 3 represent the work
together, the loss in kinetic energy due to done in moving a particle from A to B
collision is along three different paths 1, 2, 3
(A) 40 J (B) 60 J respectively (as shown) in the gravitational
(C) 100 J (D) 140 J field of a point mass m, find the correct
relation between W 1, W 2 and W 3
34. A force-time graph for a linear motion is
shown in figure where the segments are
circular. The linear momentum gained
between zero and 8 second is

+2
Force (newtons)

(A) W 1 > W 2 > W 3

Time (second)
(B) W 1 = W 2 = W 3
2 4 6 8 (C) W 1 < W 2 < W 3
–2 (D) W 2 > W 1 > W 3

(A) 2 newton  second 39. A uniform chain of length 2m is kept on a

(B) Zero newton  second table such that a length of 60cm hangs
(C) 4 newton  second freely from the edge of the table. The total
mass of the chain is 4kg. What is the work
(D) 6 newton  second done in pulling the entire chain on the
table
35. Figure shows the F-x graph. Where F is (A) 7.2 J (B) 3.6 J
(C) 120 J (D) 1200 J
the force applied and x is the distance
covered 40. An engine pumps water through a hose
pipe. Water passes through the pipe and
by the body along a straight line path.
leaves it with a velocity of 2 m/s. The mass
Given that F is in newton and x in metre,
per unit length of water in the pipe is 100
what is the work done ?
kg/m. What is the power of the engine?
(A) 10 J (B) 20 J
(A) 400 W (B) 200 W
(C) 30 J (D) 40 J
(C) 100 W (D) 800 W

PG #4
41. The force constant of a wire is k and that 48. The energy required to accelerate a car
of another wire is 2k. When both the wires
from 10 m/s to 20 m/s is how many times
are stretched through same distance, then
the work done the energy required to accelerate the car
(A) W2  2W12 (B) W2  2W1 from rest to 10 m/s
(C) W2  W1 (D) W2  0.5W1
(A) Equal (B) 4 times
42. A mass of 0.5kg moving with a speed of (C) 2 times (D) 3 times
1.5 m/s on a horizontal smooth surface,
collides with a nearly weightless spring of
force constant k  50 N / m . The maximum 49. A body of mass 2 kg slides down a curved
compression of the spring would be track which is quadrant of a circle of radius
(A) 0.15 m (B) 0.12 m
(C) 1.5 m (D) 0.5 m 1 metre. All the surfaces are frictionless. If

43. A car of mass m starts from rest and the body starts from rest, its speed at the
accelerates so that the instantaneous bottom of the track is
power delivered to the car has a constant
magnitude P0. The instantaneous velocity
of this car is proportional to :
(A) t2P0 (B) t1/2
t
(C) t–1/2 (D)
m
44. Power of a water pump is 2 kW. If
g  10 m / sec 2 , the amount of water it can
raise in one minute to a height of 10 m is
(A) 2000 litre (B) 1000 litre (A) 4.43 m/sec (B) 2 m/sec
(C) 100 litre (D) 1200 litre (C) 0.5 m/sec (D) 19.6 m/sec

45. How much work does a pulling force of 40

N do on the 20 kg box in pulling it 8 m 50. Match the column I with column II.
across the floor at a constant speed. The
pulling force is directed at 60° above the Column I
horizontal (i) When a body does work against friction,
(A) 160 J
(B) 277 J its kinetic energy
(C) 784 J (ii) Work done by a body is
(D) None of the above
(iii) Power of a body varies inversely as
46. Work done in time t on a body of mass m (iv) When work done over a closed path is
which is accelerated from rest to a speed v
in time t1 as a function of time t is given by zero
1 v v 2 Column II
(A) m t2 (B) m t
2 t1 t1 (p) independent of time
2
1 mv 2 1 v 2 2
(q) time
(C)   t (D) m t
2  t 1  2 t12 (r) force must be conservative
47. The slope of kinetic energy displacement (s) decreases
curve of a particle in motion is (A) i-p,ii-q, iii-r,iv-s
(A) Equal to the acceleration of the particle
(B) Inversely proportional to the (B) i-q,ii-r, iii-s,iv-p
acceleration (C) i-s,ii-r, iii-q,iv-p
(C) Directly proportional to the
acceleration (D) i-s,ii-p, iii-q,iv-r
(D) None of the above

PG #5