The straight forward answer to ‘what is mechanical energy’ is that it is the sum of energy in a mechanical system. This energy includes both kinetic energy(energy of motion) and potential energy(stored energy).
Objects have mechanical energy if they are in motion and/or if they are at some position relative to a zero potential energy position. A few examples are: a moving car possesses mechanical energy due to its motion(kinetic energy) and a barbell lifted high above a weightlifter’s head possesses mechanical energy due to its vertical position above the ground(potential energy).
Kinetic energy is the energy of motion. An object that has motion, vertical or horizontal motion, has kinetic energy. There are many forms of kinetic energy: vibrational (the energy due to vibrational motion), rotational (the energy due to rotational motion), and translational (the energy due to motion from one location to another).
Potential energy is the energy stored in a body or in a system due to its position in a force field or its configuration. The standard unit of measure for energy and work is the joule. The term “potential energy” has been used since the 19th century.
Because of the different components of mechanical energy, it exists in every system in the universe. From a baseball being thrown to a brick falling off of a ledge, mechanical energy surrounds us. Defining what is mechanical energy is easy, but finding examples of it are even easier.
We have written many articles about mechanical energy for Universe Today. Here’s an article about how generators work, and here’s an article about what is energy.
We’ve also recorded an entire episode of Astronomy Cast all about Gravity. Listen here, Episode 102: Gravity.