In an elastic collision, momentum is conserved as well as well as?

A lead bullet of mass 0.05kg is fired with a velocity of 200ms\(^{-1}\) into a block of mass 0.95kg. Given that the lead block can move freely, the final kinetic energy after impact is?

A ball of mass 0.1kg is thrown vertically upwards with a speed of 10ms\(^{-1}\) from the top of a tower 10m high. Neglecting air resistance, its total energy just before hitting the ground is? (Take g = 10ms\(^{-2}\))

A car of mass 800kg attains a speed of 25m/s in 20secs. The power developed in the engine is?

A man weighing 200 N runs up a staircase in 5s. If the height of the staircase is 9 m, calculate the power of the man.