Chapter 16 & 17

1. Chapter 16 & 17 Heat and Temperature

2. Title : Heat and Temperature Date: Temperature Temperature Scale Fahrenheit Celsius Kelvin Energy Transfer Conduction Convection Radiation Conductors and Insulators Kinetic Energy Graph

3. Temperature • Temperature is a measure of how hot or cold something is • It is a measure of the average kinetic energy of a particles in an object

4. Temperature • All particles have kinetic energy because they are constantly in motion • As the average kinetic energy of the particles in an object increases, the object’s temperature increases

5. Temperature • To measure temperature, we use thermometers • Thermometers use expansion liquids such as mercury or colored alcohol to measure temperature • The liquids expand when the temperature increases and contract as it decreases

6. Temperature Scale • There are three different temperature scales • Fahrenheit • Celsius • Kelvin

7. Fahrenheit Scale • Gabriel Fahrenheit was a German physicist and was the first person to use a mercury thermometer in 1714 • Units is °F • Water freezes at 32 °F • Body temperature 98.6°F • Water boils at 212°F • Used primarily only in the United States

8. Celsius Scale • Anders Celsius, a Swedish astronomer invented the centigrade scale in 1742. • Unit is °C • Water freezes at 0°C • Room temperature 25°C • Water boils at 100°C • Since 1948 most countries have used the SI or metric unit of conversion

9. Kelvin Scale • 1848 William Thomson (Lord Kelvin) • Kelvin scale is based on absolute zero • There are no negative temperatures in Kelvin • Kelvin does not use the degree sign • Water boils at 373.15 Kelvin

10. Relating Temperature to Energy Transfer • When two objects that are different temperatures are touching, energy will be transferred from one to the other • Holding a piece of ice will cause the ice to melt because you are transferring heat to the ice

11. Relating Temperature to Energy Transfer • Temperature changes indicate an energy transfer • Heat is the energy transferred between object that are different temperatures • The heat transfer is always from the higher temperature to the lower temperature

12. Energy Transfer • Heat energy can be transferred in three ways: • Conduction • Convection • Radiation

13. Conduction • Conduction occurs between objects in direct contact • Thermal conduction is the transfer of energy through a material

14. Convection • Convection results from the movement of warm fluids • Convection current is any movement of matter that results from vertical, circular, or cyclical movement

15. Radiation • Radiation is the energy that is transferred as electromagnetic waves • When molecules in your skin absorb energy, the average kinetic energy and temperature of skin increases

16. Conductors and Insulators • A conductor is a material through which energy can be easily transferred as heat • Example: pan conducting energy when heating food on the stove • An insulator is a material that transfers heat poorly • Example: The handle of the pan won’t get hot because it is an insulator

17. Conductors and Insulators • Heat energy is transferred through particle collisions • Gases are poor conductors of heat because the particles are far apart • Metals tend to be good conductors • Plastics tend to be poor conductors

18. Kinetic Energy • Heat raises an object’s temperature or changes the object’s state