Motion Worksheet-9

Motion Worksheet-9

31. A bus increases its speed from 36 km/h in 10 seconds. Its acceleration is :

A. 5 m/s²           B. 2 m/s²           C. 3.6 m/s²        D. 1 m/s²

32. A bus moving along a straight line at 20 m/s undergoes an acceleration of 4 m/s². After 2 seconds ,its speed will be :

A. 8 m/s             B. 12 m/s           C. 16 m/s           D. 28 m/s

33. The slope of a speed-time graph gives :

A. Distance traveled                    B. Velocity

C. Acceleration                             D. Displacement

34. The area under a speed-time graph represents a physical quantity which has the unit of :

A. M                    B. m²                  C. m/s^–1             D. m/s^–2

35. If the displacement of an object is proportional to the square of time, then the object is moving with :

A. Uniform velocity                      B. Uniform acceleration

C. Increasing acceleration         D. Decreasing acceleration

36. Four cars A, B, C and D are moving on a leveled, straight road. Their distance-time graphs are shown in the given figure. Which of the following is the correct statement regarding the motion of these cars ?

A. Car A is faster than car D.

B. Car B is the slowest

C. Car D is mass faster than the car C

D. Car c is the slowest

37. A car of mass 1000 kg is moving with a velocity of 10 m/s^–1. If the velocity-time graph for this car is a horizontal line parallel to the time axis, then the velocity of car at the end of 25 s will be :

A. 25 m/s^–1        B. 40 m/s^–1       C. 10 m/s^–1        D. 250 m/s^–1

38. A motorcycle is being driven at a speed of 20 m/s when brakes are applied to bring it to rest in 5 seconds. The deceleration produced in this case will be :

A. +4 m/s^–2                                   B. –4 m/s^–2

C. +0.25 m/s²                               D. –0.25 m/s²

39. A sprinter is running along the circumference of a big sports stadium with constant speed. Which of the following do you think is changing in this case ?

A. Magnitude of acceleration being produced

B. Distance covered by the sprinter per second

C. Direction in which the sprinter is running 

D. Centripetal force acting on the sprinter

40. In the speed-time graph for a moving object shown here, the part which indicates uniform retardation:

A. ST                   B. QR                  C. RS                  D. PQ

Answer:

31. D

32. D

Explanation: Here u = 20 m/s

a = 4 m/s²

t = 2 sec

Putting the values in equation of motion

v = u + at

v = 20 + 4 × 2 = 28 m/s

33. C

34. A

Explanation: In speed time graph the distance travelled by the body in a given time is equal to the area between the speed time graph and the time axis. The unit of distance is meter or kilometer.

35. B

36. B

37. C

Explanation: Velocity will be constant,

38. A

Explanation: Here u = 20 m/s

v = 0 m/s ( motorcycle is coming to rest)

t = 5 sec

Put the values in equation of motion

v = u + at

0 = 20 + a × 5

A = - 4 m/s²

Here if we talk about acceleration it will be negative but in the question deceleration is asked so it will be positive.

39. C

40. C