What is mechanical energy?

• A. The energy of heat in molecules.
• B. The energy stored in chemical bonds.
• C. The energy of motion or position, used to move objects.
• D. The energy of light traveling in waves.

Answer: (C)

Mechanical energy is the energy an object or system has because of its motion or its position in a force field. It combines kinetic energy (energy of motion) and potential energy (energy of position). The total mechanical energy is the sum of these two parts, and in a frictionless situation it stays constant as energy shifts between motion and height.

That’s why the best description is energy of motion or position used to move objects. Heat energy describes microscopic molecular motion (thermal energy), chemical energy is stored in chemical bonds, and radiant energy is energy carried by light waves. An example: a swinging pendulum has mostly potential energy at the highest point and mostly kinetic energy at the lowest point, with the total mechanical energy remaining roughly the same.