The force exerted by a diving board is conservative, provided the internal friction is negligible. Assuming friction is negligible, describe changes in the potential energy of a diving board as a swimmer dives from it, starting just before the swimmer steps on the board until just after his feet leave it.

According to law of conservation of energy, the total energy of the system remains conserved, it is only transformed from one form to another.

Before the swimmer dives off from the diving board, he presses the diving board downwards. The board stores elastic potential energy until it is pressed to the maximum limit.

At the highest point, the potential energy stored in the diving board starts converting into kinetic energy due to which the board is pushed up in the air.

As the board rises in the air, the kinetic energy the diving board starts converting to the potential energy until the board attains a certain height where all the kinetic energy of the board is converted into potential energy.

At this point the swimmer dives off the board and start falling back towards the ground during which the potential energy starts converting into kinetic energy.

When the swimmer hits the water, some of its kinetic energy is converted into sound energy and heat energy of water.