Temperature is defined as what?

• A. A measure of the average kinetic energy in a system
• B. The energy transferred between objects that are at different temperatures
• C. The total kinetic energy of all molecules in a system added together
• D. The amount of energy required to raise the temperature of a 1 gram substance by 1 degree Celsius

Answer: (A)

Temperature is a measure of how vigorously the particles in a substance are moving on average. It reflects the average kinetic energy of those particles: higher average motion means a higher temperature. This is why two objects at the same temperature can have different amounts of energy if they contain different amounts of matter—the total kinetic energy depends on both how fast the particles are moving on average and how many particles there are. The energy transferred between objects at different temperatures is heat, not temperature itself. The energy needed to raise a substance’s temperature by 1 degree Celsius is a property related to heat capacity (specific heat), not the definition of temperature.