1. THERMAL ENERGY OUTLINE
Source: MGH CHAPTER 5 / Thermal Energy, Temperature and Heat

2. A. Kinetic and potential Energy
1. Any moving object has kinetic energy. 2. The energy that is stored due to the interactions between objects is called potential energy. 3. A moving soccer ball that has been kicked into the air has kinetic energy and potential energy; together they make up the mechanical energy of the ball

3. B. What is thermal Energy?
1. The particles that make up matter have kinetic energy and potential energy.
2. The sum of the kinetic energy and the potential energy in the particles that make up an object is called thermal energy.
3. Thermal energy describes the energy of the particles in solids, liquids, and gases.

4. C. What is temperature?
1. Scientists define temperature in terms of kinetic energy.
2. The average kinetic energy of the particles that make up a material is the temperature of the material.
a. A material with a(n) high temperature has particles that have a greater average kinetic energy than a material with a(n) lower temperature.
b. Particles whose average kinetic energy is large are moving at a(n) greater average speed than particles whose average kinetic energy is smaller.

5. C. What is temperature? (continued)
3. Two materials can have the same temperature but different thermal energy. For example, ice and water have the same average kinetic energy, but liquid water has greater thermal energy because its particles have greater potential energy than those of ice.
4. A(n) thermometer is used to measure temperature.
a. A(n) bulb thermometer has a liquid that expands and rises in a(n) glass tube when its temperature goes up; the liquid contracts and its level drops when the temperature goes down.
b. A(n) electronic thermometer measures the resistance in an electronic circuit and converts this measurement into a(n) temperature.

6. What is temperature? (Continued)
5. Scientists around the world use the Celsius scale.
a. Water freezes at 0ºC and boils at 100ºC.
b. The Kelvin scale is also used by scientists; water freezes at 273 K and boils at 373 K.
c. The lowest possible temperature for any material is called absolute zero and is 0 K; at this temperature the particles in a material would not be moving and would have no kinetic energy.

7. What is heat?
1. Heat is the movement of thermal energy from a warmer object to a(n) cooler object.
2. All objects have thermal energy, but heating occurs only when thermal energy is transferred from one object to another object.
a. The rate at which heating occurs depends on the difference in temperature between two objects; the greater the difference, the faster heat is transferred.
b. Heating continues until all substances that are in contact have reached the same temperature.

8. Discussion Question
If no object has ever reached 0 degrees Kelvin, how is the Kelvin scale useful for scientists?

9. Possible answers to discussion question:
In some fields of science, getting materials very, very cold might be useful, for example, electric current and other forms of energy travel more easily through very cold materials; when working with low temperatures, it is easier to make calculations and communicate using a scale that uses positive rather than negative numbers.