Mechanical energy

This chapter discusses mechanical energy. Energy is usually defined as the capacity for doing work. Mechanical energy is the capacity possessed by a body to do mechanical work. Therefore, it is a store of energy, which, when released, can readily be converted into mechanical work. Consequently, energy and work done will be interdependent. Mechanical energy can exist in two forms. The body may have a capacity for doing work either because it has a height advantage—that is, it is initially at some higher level than the new level used as reference—or, because it has a velocity. A body is said to acquire potential energy when it is raised vertically, thus, giving it a height advantage. Work is done on the body by raising it against the force of gravity, and so an extra store of energy is acquired by the body equivalent to the external work done on it.