Railway Science (Physics-Force and Pressure) (Part-III)

Total Questions: 50

41. An object of 2 kg is moving with an acceleration of 4 m/s². The net force acting on it is [RRB Group D 22/09/2018 (Afternoon)]

Correct Answer: (b) 8.0 N
Solution:

Given, Mass = 2 kg, Acceleration = 4 m/s².
Force = Mass × Acceleration = 2 × 4 = 8 N.

42. An object of mass 80 kg is moving with a velocity of 60 ms⁻¹. Then the momentum of the object is _____ . [RRB Group D 22/09/2018 (Afternoon)]

Correct Answer: (d) 4800 kgms⁻¹
Solution:

Given, Mass = 80 kg. Velocity = 60 ms⁻¹.
Momentum = Mass × Velocity = 80 × 60 = 4800 kg ms⁻¹.

43. A ball is thrown vertically upward with a velocity of 20 m/s. After 3s, the magnitude of its displacement is (take g=10 m/s²) [RRB Group D 22/09/2018 (Afternoon)]

Correct Answer: (b) 15 m
Solution:

44. A body of mass 30 kg moves with an initial speed of 20 m/s. If a retarding force of 60 N is applied, how long does the body take to stop? [RRB Group D 22/09/2018 (Evening)]

Correct Answer: (b) 10 s
Solution:

45. A 2000 kg truck moving at 10 m/s collides with a car standing at a traffic light. After the collision, both move together with a speed of 8m/s. The mass of the car is ______. [RRB Group D 23/09/2018 (Morning)]

Correct Answer: (b) 500 kg
Solution:

46. Body A whose mass is 2 kg and body B whose mass is 3 kg are moving towards each other with the velocity of 4 m/s and 2 m/s respectively, at the time of collision with each other the elastic collision will be _________. [RRB Group D 23/09/2018 (Morning)]

Correct Answer: (b) In the opposite direction
Solution:

47. A car starts from rest and moves with uniform acceleration. If it reaches a velocity of 20 m/s in 4 s, the acceleration of the car is ________ . [RRB Group D 23/09/2018 (Evening)]

Correct Answer: (b) 5 ms⁻²
Solution:

48. What will be the momentum of an object of mass 1/2 m whose velocity is 2v [RRB Group D 24/09/2018 (Morning)]

Correct Answer: (b) mv²
Solution:

Given, mass = 1/2 m and velocity = 2v.
∴ Momentum = mass × velocity
⇒ momentum = 1/2 m × 2v = mv.

49. When a continuous force acts on an object of 8 kg mass for 2 seconds, it increases the velocity of the object from 4 𝑚𝑠⁻¹ to 9 4 𝑚𝑠⁻¹. What is the magnitude of the force applied? [RRB Group D 24/09/2018 (Afternoon)]

Correct Answer: (b) 20 N
Solution:

50. A 70 kg person pushes a 50 kg person with a force of 50 N. By what force has the 50 kg person pushed the other person ? [RRB Group D 24/09/2018 (Afternoon)]

Correct Answer: (d) 50N
Solution:

This is because of Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. In this case, the 70 kg person pushing with 50 N is the action, and the 50 kg person pushing back with 50 N is the reaction.