Linear Kinetics
Mechanical energy: On many occasions during human movement there are interchanges between kinetic and potential energy. That is, as kinetic energy decreases potential energy may increase. This interchange can be observed when throwing a ball into the air as shown below.
Notice above how KE is zero at the apex because velocity is zero and that PE is zero just before landing because height above the ground is nearly zero. All projectiles will experience the above interchange between KE and PE. One important message here is that total mechanical energy (KE + PE) of the body is constant while airborne. This constant is known as the law of conservation of energy. The website below provides a simulation of the law and may be helpful to view.