Final answer:
Mechanical energy consists of kinetic energy and potential energy, examples being a rolling ball and a book on a shelf, respectively. It remains constant under conservative forces, but can change with nonconservative forces like friction.
Step-by-step explanation:
Mechanical energy is the energy associated with the motion and position of an object, a form of energy that is the sum of kinetic energy and potential energy. The two types are:
- Kinetic energy (EK): The energy of a body due to its motion. For example, a rolling ball on the ground has kinetic energy.
- Potential energy (Ep): The stored energy of position possessed by an object. A classic example is a book placed on a high shelf, which has gravitational potential energy.
When only conservative forces such as gravity and spring forces act on a system, the mechanical energy of the system remains constant. However, in the presence of nonconservative forces, like friction, the total mechanical energy of a system may change. An example of mechanical work is when you lift a brick, using mechanical energy to counteract the force of gravity.