Wednesday, 26 October 2016

3 Motion and Force MCQs with solution

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
(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

 1 c 21 c 2 a 22 b 3 b 23 b 4 a 24 b 5 c 25 c 6 b 26 a 7 b 27 b 8 d 28 b 9 b 29 c 10 c 30 b 11 b 31 d 12 b 32 d 13 d 33 b 14 a 34 d 15 c 35 b 16 d 36 b 17 b 37 a 18 d 38 d 19 c 39 c 20 a 40 b