Which term describes energy that comes from both motion and position, i.e., the sum of kinetic and potential energy?

• A. Energy
• B. Mechanical energy
• C. Thermal energy
• D. Light energy

Answer: (B)

Mechanical energy is the energy that comes from both motion and position—the sum of kinetic energy, which depends on motion, and potential energy, which depends on position. This combined energy describes how much work a system can do due to how fast it’s moving and where it is in a field or relative to a reference point. In a frictionless system, this total stays constant even as energy swaps between kinetic and potential forms. For example, a swinging pendulum has high potential energy at the peak (it’s high and not moving much) and high kinetic energy at the bottom (it’s moving fastest and is lowest), yet the total mechanical energy remains the same.

The other terms refer to different concepts. Energy is a general idea, while thermal energy relates to microscopic motion and temperature, and light energy is radiant energy carried by light. None of these capture the idea of the total energy due to motion and position that mechanical energy represents.