Which object has less thermal energy?
a bowl of cereal at a temperature of 20°C a bowl of cereal at a temperature of 15°C
The objects are identical except for their temperatures.
All solids, liquids, and gases are made of matter. Matter is made up of tiny particles that are always moving. The energy from the motion of these particles is called thermal energy.
Temperature measures how hot or cold matter is. If the particles in matter slow down, the temperature goes down. The matter now has both less thermal energy and a lower temperature.
The two bowls of cereal have the same mass but different temperatures. Since the 15°C bowl of cereal is colder than the 20°C bowl of cereal, it has less thermal energy.