# Units and Measurements Multiple Choice Questions

Q1. If the path length covered by a body is zero then

1. its displacement is zero.
2. the displacement > 0.
3. the displacement < 0.
4. displacement may or may not be zero.

Answer :- (1) its displacement is zero.

Q2. A man starts from his home with a speed of 4 km/h on a straight road up to his office 5 km away and returns to home, then the path length covered is

1. 10 km
2. 5 km
3. zero
4. -5 km

Q3. Which of the following measurements could be a velocity?

1. 5 m North
2. 5 m/s North
3. 5 s North
4.     5 m/s2

Answer :- (2) 5 m/s North

Q4. An object is in uniform motion along a straight line if it

1. moves equal distances in unequal intervals of time.
2. moves unequal distances in unequal intervals of time
3. moves equal distances in equal intervals of time.
4. does not move

Answer :- (3) moves equal distances in equal intervals of time.

Q5. An aeroplane lands on a runway with a velocity of 50 m/s. It decelerates at 10 m/sto a velocity of 20 m/s. Find the time elapsed.

1. 3 s
2. 1 s
3. 2 s
4. 4 s

Q6. Which of the following quantity remains constant during the uniform circular motion?

1. Velocity
2. Angular acceleration
3. Angular velocity
4. Speed

Q7. On acceleration-time graph the area under the curve equals the:

1. Displacement
2. Change in velocity
3. Change in acceleration
4. Meaningless

Answer :- (2) Change in velocity

Q8. The position x of a particle varies with time (t) as x = 3t– 2t3
The acceleration of the particle will be zero at time

1. 1
2. 3 / 2
3. 1 / 2
4. 0

Answer :- (3) 1 / 2

Q9. On acceleration-time graph, a horizontal line indicates:

1. zero displacement
2. Zero acceleration
3. constant velocity
4. Constant acceleration

Q10. The steeper the tangent drawn to the position time graph, the larger will be the speed of the object at that instant. Choose the correct option

1. True
2. False
3. Can’t predict
4. none

Q11. A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. How much further will it penetrate before coming to rest?

1. 1 cm
2. 2 cm
3. 3 cm
4. 4 cm

Q12. If a car increases its speed by unequal amounts in equal interval of time, then the car is said to be moving with

1. uniform acceleration
2. non uniform acceleration
3. uniform velocity
4. zero velocity

Answer :- (2) non uniform acceleration

Q13. An orange is dropped from a building. One second after dropping the orange, it falls one storey. Two seconds after the orange is dropped, how many stories has it fallen?

1. 1 story
2. 2 stories
3. 3 stories
4. 4 stories

Q14. bWhat does the slope of a velocity – time represent?

1. Displacement
2. Momentum
3. Acceleration
4. Distance

Q15. Which of the following quantity remains constant during the uniform circular motion?

1. Velocity
2. Angular acceleration
3. Angular velocity
4. Speed

Q16. On velocity-time graph, a horizontal line indicates:

1. zero displacement
2. zero acceleration
3. zero velocity
4. constant acceleration

Q17. A stone and a feather are dropped from the same height H=1 m in an evacuated chamber. Which object will reach the bottom of the chamber first?

1. The stone reaches the bottom first
2. The feather reaches the bottom first
3. Both stone and feather reach at the same time
4. Cannot answer unless you know the mass of the stone and feather

Answer :- (3) Both stone and feather reach at the same time

Q18. The dimensions of (change in velocity / time) is

1. [LT-1]
2. [LT-2]
3. [L/T-2]
4. [L/T-1]

Q19. The magnitude of average velocity is equal to the average speed if the motion of an object is along a straight line and in the same direction.

1. True
2. False
3. sometimes true and sometimes false
4. can’t predict

Q20. The kinematic equation of motion v = u+at is not applicable if :

1. acceleration is not constant
2. velocity is not constant
3. displacement is not constant
4. motion is non-uniform.

Answer :- (1) acceleration is not constant

Q21. 36 km/h is equal to:

1. 600 ms-1
2. 10 ms-1
3. 129. 6 ms-1
4. 12.96 ms-1

Q22. Slope of displacement time graph or x-t graph gives us the particles’ ____________.

1. Displacement
2. Velocity
3. Acceleration
4. Deceleration

Q23. The area of acceleration time graph indicates:

1. Acceleration
2. Average Speed
3. Velocity
4. Displacement

Q24. If the signs of the velocity and acceleration of a particle are the same, the speed of the particle ______________.

1. Decreases
2. Increases
3. Remains same
4. Cannot conclude anything

Q25. The motion of a freely falling body is an example of:

1. uniformly accelerated motion
2. non uniformly accelerated motion
3. uniform motion
4. none of the above

Answer :- (1) uniformly accelerated motion

Q26. Choose the incorrect statement

1. Time rate of change of displacement is called velocity
2. Velocity is a vector quantity
3. Velocity gives no idea about the direction of motion of the objects
4. Velocity can be positive, negative or zero

Answer :- (3) Velocity gives no idea about the direction of motion of the objects

Q27. A train 100 m long is running with speed of 40 km/h. In what time shall it cross a bridge of 1 km length?

1. 99 s
2. 100 s
3. 101s
4. 95 s

Q28. The position of a particle is given by x = at3  where a is  a constant. Find the velocity as a function of time.

1. v = a.t4/4
2. v = a.3/t2
3. v = a.3t2
4. v = 3t2

Answer :- (3) v = a.3t2

Q29. A ball is thrown vertically upward. At the highest point in its path, which of the following statements is correct?

1. The velocity and acceleration are both zero
2. The velocity is zero and the acceleration is pointing down
3. The acceleration is zero and the velocity is pointing down
4. The acceleration is zero and the velocity is pointing up

Answer :- (2) The velocity is zero and the acceleration is pointing down

Q30. Two escalators move people up and down between floors of a shopping mall at the same rate, either up or down. What of the following statements regarding the motion of the escalators is true?

1. The escalators have different speeds and velocities.
2. The escalators have the same velocity, but different speeds.
3. The escalators have the same speed, but different velocities.
4.  The escalators have the same speed and velocity.

Answer :- (3) The escalators have the same speed, but different velocities.

Q31. If a body does not change its direction during the course of its motion, then

1. Path length and displacement are equal
2. Path length is greater than displacement
3. Displacement is greater than path length
4. Path length is either greater or equal to displacement

Answer :- (1) Path length and displacement are equal

Q32. Rain falls at a speed of 50m/s and a child walks on a straight road from east to west at a speed of 100m/s. To find the direction in which the child should hold the umbrella use

1. relative speed of child with respect to rain
2. relative speed of rain with respect to child
3. resultant speed of child and rain
4. resultant speed of rain and child

Answer :- (2) relative speed of rain with respect to child

Q33. The velocity-time graph will be a straight line with a non-zero slope for the motion of a ball which is launched vertically up and then comes back down under the influence of gravitational acceleration. Choose the correct option

1.     True
2.     False
3.     Canâ€™t predict
4.     none

Q34.The ratio of displacement to distance is

1. Less than 1
2. Equal to 1
3. Greater than 1
4. Either less than or equal to 1

Answer :- (4) Either less than or equal to 1

Q35. The speed of an object in a particular direction is called

1. uniform speed
2. velocity
3. distance
4. displacement

Q36. For uniform circular motion:

1. velocity is along circle and acceleration is towards the centre of circle
2. velocity and acceleration is towards the centre of circle
3. velocity is along tangent and acceleration is towards the centre of circle
4. velocity and acceleration is along the tangent

Answer :- (3) velocity is along tangent and acceleration is towards the centre of circle

Q37. A boy throws up a ball in a stationary lift and the ball returns to his hands in 10 s. Now if the lift starts moving up at a speed of 5 m/s. The time taken for a ball thrown straight up to return to his hands is:

1. less than 10 s
2. more than 10 s
3. equal to 10 s
4. insufficient information given

Answer :- (3) equal to 10 s

Q38. Which of the following is not an example of a rectilinear motion?

1. A car moving on a straight road
2. A rain drop falling towards the earth
3. A wooden block sliding down the inclined plane
4. A car moving in a circular path

Answer :- (4) A car moving in a circular path

Q39. Two stones of different masses are thrown vertically upward with same initial velocity. Which one will rise to a greater height?

1. Stone of lower mass
2. Stone of higher mass
3. Both will rise to the same height
4. Information given is insufficient

Answer :- (3) Both will rise to the same height

Q40. The displacement of a particle starting from rest (at t = 0) is given by s = 6t2-t3
The time in seconds at which the particle will attain zero velocity again, is

1. 2
2. 4
3. 6
4. 8