# Physics MCQs for Class 12 with Answers Chapter 3 Motion in a Straight Line

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#### MCQ Questions for Class 11 Physics Chapter 3 Motion in a Straight Line

Q.1. Two balls A and B of same mass are thrown from the top of the building. A thrown upward with velocity v and B, thrown down with velocity v, then
(a) velocity A is more than B at the ground
(b) velocity of B is more than A at the ground
(c) both A &B strike the ground with same velocity
(d) None of these

Q.2. The numerical ratio of displacement to distance for a moving object is
(a) always less than 1
(b) always equal to 1
(c) always more than 1
(d) equal to or less than 1

Q.3. Which of the following can be zero, when a particle is in motion for some time?
(a) Distance
(b) Displacement
(c) Speed
(d) None of these

Q.4. The incorrect statement(s) from the following is/are
I.
A body having zero velocity will not necessarily have zero acceleration
II. A body having zero velocity will necessarily have zero acceleration
III. A body having uniform speed can have only uniform acceleration
IV. A body having non-uniform velocity will have zero acceleration
(a) II, III and IV
(b) I and II
(c) II and III
(d) IV only

Answer Answer: (a) When the body is projected vertically upward then at the highest point its velocity is zero but acceleration is not equal to zero (g = 9.8m/s2).

Q.5. If distance covered by a particle is zero, what can you say about its displacement?
(a) It may or may not be zero
(b) It cannot be zero
(c) It is negative
(d) It must be zero

Answer Answer: (d) Distance covered by a particle is zero only when it is at rest. Therefore, its displacement must be zero.

Q.6. The location of a particle has changed. What can we say about the displacement and the distance covered by the particle?
(a) Neither can be zero
(b) One may be zero
(c) Both may be zero
(d) One is +ve, other is –ve

Answer Answer: (a) When location of a particle has changed, it must have covered some distance and undergone some displacement.

Q.7. The displacement of a body is zero. The distance covered
(a) is zero
(b) is not zero
(c) may or may not be zero
(d) depends upon the acceleration

Q.8. Area under velocity-time curve over a given interval of time represents
(a) acceleration
(b) momentum
(c) velocity
(d) displacement

Q.9. The distance travelled by a body is directly proportional to the time taken. Its speed
(a) increases
(b) decreases
(c) becomes zero
(d) remains constant

Q.10. The slope of the tangent drawn on position-time graph at any instant is equal to the instantaneous
(a) acceleration
(b) force
(c) velocity
(d) momentum

Q.11. An object accelerated downward under the influence of force of gravity. The motion of object is said to be
(a) uniform motion
(b) free fall
(c) non uniformly accelerated motion
(d) None of these

Q.12. Free fall of an object (in vacuum) is a case of motion with
(a) uniform velocity
(b) uniform acceleration
(c) variable acceleration
(d) constant momentum

Answer Answer: (b) Free fall of an object (in vacuum) is a case of motion with uniform acceleration.

Q.13. A ball thrown vertically upwards after reaching a maximum height h, returns to the starting point after a time of 10 s. Its displacement is
(a) h
(b) 2 h
(c) 10 h
(d) zero

Answer Answer: (d) As ball returns to starting point so displacement is zero.

Q.14. The slope of velocity-time graph for motion with uniform velocity is equal to
(a) final velocity
(b) initial velocity
(c) zero
(d) none of these

Answer Answer: (c) The velocity-time graph for a uniform motion is a straight. line parallel to time axis. Its slope is zero.

Q.15. Choose the wrong statement from the following.
(a) The motion of an object along a straight line is a rectilinear motion
(b) The speed in general is less than the magnitude of the velocity
(c) The slope of the displacement-time graph gives the velocity of the body
(d) The area under the velocity-time graph gives the displacement of the body

Answer Answer: (b) The speed in general 􀁴 the magnitude of velocity

Q.16. The ratio of the numerical values of the average velocity and average speed of a body is
(a) unity
(b) unity or less
(c) unity or more
(d) less than unity

Q.17. If the displacement of a body varies as the square of elapsed time, then its
(a) velocity is constant
(b) velocity varies non-uniformly
(c) acceleration is constant
(d) acceleration changes continuously

Q.18. The total distance travelled by the body in the given time is equal to
(a) the area which v– t graph encloses with displacement axis
(b) the area which x – t graph encloses with time axis
(c) the area which v – t graph encloses with time axis
(d) the area which a – t graph encloses with axis

Q.19. A truck and a car are moving with equal velocity. On applying the brakes both will stop after certain distance, then
(a) truck will cover less distance before rest
(b) car will coverless distance before rest
(c) Both will cover equal distance
(d) None of these

Q.20. If Position of a particle is given by x = (4t2 – 8t), then which of the following is true?
(a) Acceleration is zero at t = 0
(b) Velocity is zero at t = 0
(c) Velocity is zero at t = 1s
(d) Velocity and acceleration will never be zero

Q.21. A man throws balls with same speed vertically upwards one after the other at an interval of 2 sec. What should be the speed of throw so that more than two balls are in air at any time ?
(a) Only with speed 19.6 m/s
(b) More than 19.6 m/s
(c) At least 9.8 m/s
(d) Any speed less then 19.6 m/s.