A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 ms^-1. Calculate when and where the two stones will meet.

A ball thrown up vertically returns to the thrower after 6 s. Find

(a) the velocity with which it was thrown up,

(b) the maximum height it reaches, and

(c) its position after 4s.

Why a block of plastic when released under water come up to the surface of water?

The volume of 50 g of a substance is 20 cm³. If the density of water is 1 gcm^-3, will the substance float or sink?