Chapter 16 & 17 Heat and Temperature

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

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

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

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

Temperature Scale There are three different temperature scales 1.Fahrenheit 2.Celsius 3.Kelvin

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

Celsius Scale Anders Celsius, a Swedish astronomer invented the centigrade scale in 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

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 Kelvin

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

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

Energy Transfer Heat energy can be transferred in three ways: 1.Conduction 2.Convection 3.Radiation

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

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

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

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

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

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