At the surface of the water, the boy releases a stone and he falls to the bottom (5 m)

At the surface of the water, the boy releases a stone and he falls to the bottom (5 m) how much heat is released when the stone falls, if its mass is 500 g and the volume is 200 cm3

The potential energy of a body raised above the ground is equal to: m * g * h,
where m is the mass, g is the acceleration of free radiance, h is the height. When you fall, all this energy goes into the internal one. Accordingly, we get:
Q = 0.5 * 9.8 * 5≈15 J.
It should be noted that some of this energy will be released during the fall, due to friction against the water. The volume of the stone does not matter and is superfluous in the problem statement.