Temperature is a measure of the average kinetic energy of particles in an object. Higher temperatures indicate higher kinetic energy. Thermometers can measure temperature changes because substances expand with increasing temperature. Heat is the transfer of thermal energy between objects due to a temperature difference. Thermal energy can be transferred through conduction, convection, or radiation. Changes in states of matter and chemical changes both involve the transfer of heat. Energy is constantly being transferred and transformed within systems and the environment.

2. Kinetic energy is the energy of motion. All moving objects have kinetic energy.

7. The Kelvin scale is the official SI temperature scale.

13. When air (which is a mixture of gases) inside a hot-air balloon is heated, the air expands.

22. As water is heated, it becomes less dense. The warmer water rises through the cooler water above it.

30. Because of its high thermal conductivity, metal transfers energy more rapidly than cloth does.

36. Three familiar states of matter are solid, liquid, and gas.

40. As the ice melts, its temperature remains at 0°C even as more energy is added. This added energy changes the arrangement of the molecules in the ice.

44. Energy that your body can use is released when chemical compounds such as carbohydrates are broken down in your body.

46. Energy Loss During Transfer Energy conversion and transfer are not 100% efficient. This means that some energy is lost, often as heat, during physical and chemical changes.

48. When heat is lost during a transfer, that energy acts to increase the random motion of the particles it comes in contact with.