what does the law of conservation of energy state?
keep it short answer but a complete sentence
Energy cannot be created or destroyed but it can be converted from one form to another.
Law of conservation of energy states that energy can neither be
created nor destroyed, it can only be transferred from one body to
other or can be converted into other forms.
You need to remember that one form of energy may be converted into another form, while the total amount of energy is not modified, it remains constant.
Hence, the energy is never lost, but passed over or changed in form.
Hence, if you hit a ball in a state of rest by a moving ball, the moving ball stops and the ball in rest starts to move, hence, the energy is passed from one ball to another.
The energy may also suffer changes in its form, hence, kinetic energy may be converted in potential energy or potential energy may be converted in kinetic energy.
You need to remember that the energy does not disappear and the sum of all energies in univers remains constant.