question_answer

A cart of mass mg starts moving right due to a constant horizontal force F. At same time, sand starts falling into cart from a stationary hopper. Rate of loading is constant and equal to Velocity of cart at time t is

A)

B)

C)

D)

Correct Answer: A

Solution :

Let velocity of cart in v at time t. When sand particle falls onto cart, its' relative velocity with respect to cart is (backwards), so force of sand on cart is backwards.

Net force on cart is