Chapter 3 Motion and Force completely solved is from Physics book of FSC part 1.Answer key is given in the end.
Physics Chapter 3 Mcqs
3.
A body whose instantaneous and average
velocities are equal is said to have
(a)
constant acceleration (b) constant velocity
(c) variable
velocity (d)
variable acceleration
4. Inertia of a body is a measure of
its
(a)
mass (b)
weight
(c)
velocity (d) momentum
5. A body moving with velocity v has energy
E. Its momentum is
E Ev
(a)
(b) v 2
2E
(c) (d) Ev v
6. An alternate unit to kg ms1
(a) J
s (b)
N s
(c)
N m (d)
N
7. Change of linear momentum of a body is
called its (a) acceleration (b) impulse
(c)
force (d)
energy
8. A trolley of mass 3 kg moving with a
speed of 4 ms1
collides with and remains attached to a stationary trolley of mass 1 kg. Their
combined momentum, in kg ms1,
after the collision is
(a)
4 (b)
7
(c)
8 (d)
12
9. Forces in nature always occur in
(a)
single form (b)
pair form
(c)
triple form (d)
any form
10. When two bodies move like a single body
after colliding each other, the collision is said to be
(a)
perfectly elastic (b) partially elastic
(c)
perfectly inelastic (d) partially inelastic
11. As a result of an elastic collision between
two masses m1 and m2 an exchange of velocity takes place.
For collision of this type
(a)
m1 >>
m2 (b) m1
= m2
(c) m1 << m2
(c) one
of the masses must be initially at rest
12. If a shell is fired from a canon and
explodes in air, then the total
(a)
momentum increases (b) momentum
decreases
(c)
kinetic energy increases (d) kinetic
energy decreases
13. A ball thrown up with a velocity of 19.6 ms-1
returns back into the thrower’s hand after
(a) 1
s (b)
2 s
(c)
3 s (d)
4 s
15. From the top of a building a ball A is
dropped while another ball B is thrown horizontally at the same instant. Which
ball will strike the ground first?
(a)
A (b)
B
(c)
Both at the same time (d) Nothing
can be predicted
16. In case of projectile motion, the maximum
height attained by a body is equal to its range. The angle of projection with
the horizontal is
(a)
tan-1
(1) (b)
tan-1
(2)
(c)
tan-1
(3) (d)
tan-1
(4)
18. The horizontal range of a projectile is the
same for the angles
(a) 600
and 800 (b) 400 and 700
(c)
450 and 550 (d)
400 and 500
19. The time taken by a projectile to reach
maximum height is
(a)
vi sin (b)
2vi sin
2
g g
(c) vi
sin (d)
vi cos
g g
20. A ballistic trajectory is the path followed
by
(a) an
un-powered and unguided missile
(b) a
powered and guided missile
(c) an
un-powered but guided missile
(d) a
powered and guided missile
21. A snooker ball moving with velocity v
collides head-on with another snooker ball of same mass at rest. If the
collision is elastic, the velocity of the second snooker ball is
(a)
zero (b)
uncertain
(c)
v (d)
2 v
22. The time of flight of a projectile is
(a) vi sin (b)
2vi sin g g
(c)
vi sin (d)
2vi cos
2g g
23. The velocity of a projectile at the maximum
height is
(a) vi sin (b)
vi cos
(c)
maximum (d) zero
24. With increasing angle of projection, the
vertical height gained by a projectile
(a)
decreases gradually
(b)
increases gradually
(c)
first increases and then decreases (d)
remains the same.
25. The horizontal component of the velocity of
a projectile moving with initial velocity of 500 ms-1 at an angle of
600 to the x-axis is
(a)
500 ms-1 (b) 1000 ms-1
(c)
250 ms-1 (d) zero
26. A car is decelerating uniformly, its velocity
changing from 30 ms1
to 15 ms-1 in 75 m. How much further will it travel before coming to
rest?
(a)
25 m (b)
50 m
(c)
75 m (d)
100 m
28. Laws
of motion are valid in those systems which
(a)
are non-inertial (b) are inertial
(c)
are at rest (d)
are in space
31. Neutron (mass = 1 u) undergoes elastic
collision with stationary nitrogen nucleus (mass = 14 u). The velocity of
neutron after the collision is
(a)
0
(b)
less than the velocity of nitrogen atom
after collision
(c)
equal in magnitude to its initial
velocity but opposite direction
(d)
less in magnitude than its initial
velocity but with changed direction
32. Area under the velocity – time graph
represents
(a)
speed (b)
momentum
(c)
velocity (d) distance covered
33. A body thrown up with a velocity of 9.8 ms1
reaches a maximum height of
(a)
9.8 m (b)
4.9 m
(c)
19.6 m (d)
44.1 m
34. A force of 4 N acting on a body of mass 2 kg for 2 s
produces a rate of change of momentum of
(a) 1
kgms-1 (b) 2 kgms-1
(c)
4 kgms-1 (d) 8 kgms-1
35. Dimensions of impulse are
(a)
[MLT] (b)
[MLT-1]
(c)
[MLT2] (d)
[MLT2]
36. Collisions of gas molecules with the walls
of the container are the example of
(a)
inelastic collisions (b) elastic collisions
(c)
partially elastic collisions (d)
partially inelastic collisions
37. Gas molecules inside a container
constitute
(a) an
isolated system (b)
a non-isolated system
(c) a
conservative system (d) a
non-conservative system
38. A ball bouncing off a wall
(a) obeys
law of conservation of energy
(b) does
not obey law of conservation of energy (c) obeys law of conservation of momentum
(d)
does not obey law of conservation of momentum.
39. Speed of a projectile is minimum at
the
(a)
point of landing (b) point of projection
(c)
maximum height (d)
none of these
40. What happens when a system of two bodies
undergoes an elastic collision?
(a) The
momentum of the system changes
(b) The
momentum of the system does not change
(c) The
bodies come to rest after collision (d) The energy conservation law is
violated.
Answer to Chapter 3
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1
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c
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21
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c
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2
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a
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22
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b
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3
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b
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23
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b
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4
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a
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24
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b
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5
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c
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25
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c
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6
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b
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26
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a
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7
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b
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27
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b
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8
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d
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28
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b
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9
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b
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29
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c
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10
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c
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30
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b
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11
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b
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31
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d
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12
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b
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32
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d
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13
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d
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33
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b
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14
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a
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34
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d
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15
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c
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35
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b
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16
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d
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36
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b
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17
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b
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37
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a
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18
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d
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38
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d
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19
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c
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39
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c
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20
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a
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40
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b
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