Question

Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it.

Avinash can run with a speed of 8 m s⁻¹ against the frictional force of 10 N, and Kapil can move with a speed of 3 m s⁻¹ against the frictional force of 25 N. Who is more powerful and why?

The power of a motor pump is 2 kW. How much water per minute the pump can raise to a height of 10 m? (Given g = 10 m s⁻²)

An automobile engine propels a 1000 kg car (A) along a levelled road at a speed of 36 km h⁻¹. Find the power if the opposing frictional force is 100 N. Now, suppose after travelling a distance of 200 m, this car collides with another stationary car (B) of same mass and comes to rest. Let its engine also stop at the same time. Now car (B) starts moving on the same level road without getting its engine started. Find the speed of the car (B) just after the collision.