Which term describes the energy stored due to molecular motion in a system?

• A. Temperature
• B. Heat
• C. Specific heat
• D. Thermal energy

Answer: (D)

Thermal energy is the energy in a system that comes from the random motion and interactions of its molecules. It represents the internal energy tied to temperature, including both the kinetic energy of moving particles and the potential energy from their interactions. Temperature is a measure of the average kinetic energy, not the total energy stored. Heat is energy in transit due to a temperature difference, not the stored energy itself. Specific heat tells you how much energy is needed to raise the temperature of a given mass. So, the energy stored because of molecular motion in a system is thermal energy.