A football kicked by a player leaves the ground and after travelling in air reaches the ground and comes to stop at some other position on the ground. Identify the energy transformation in this process. Is energy of the ball conserved?

Kinetic energy imparted to the ball is converted into potential energy at the highest point and small part remains kinetic. Then it is converted into kinetic energy when it hits the ground. This energy is used up in overcoming the friction against air and the ground. Due to dissipation of energy in overcoming friction against air and ground, the kinetic energy of the balls is not conserved.