A stone is thrown from the top of a cliff. When is its mechanical energy higher, at the top of the cliff right before being thrown or right before hitting the ground?
The mechanical energy is defined as the combination of the kinetic energy and the potential energy. It has therefore the formula: EM = EK + EV = 1/2 · m · v2+ m · g · h being m the mass of the object, v the velocity , g the gravitational acceleration and h the height. The mechanical energy is preserved through the process of falling. Before being thrown, the only component of the mechanical energy will be its potential energy, and right before hitting the ground, the only component will the the kinetic energy, but the overall mechanical energy will have the same constant value.
