Temperature and Heat

Temperature Kinetic energy is the energy that matter has due to the movement of that matter or within the matter Kinetic energy is the energy that matter has due to the movement of that matter or within the matter Temperature- the measurement of the kinetic energy in a sample of matter Temperature- the measurement of the kinetic energy in a sample of matter

Temperature All matter is made of atoms or molecules. All matter is made of atoms or molecules. These particles move around at different speeds depending upon temperature These particles move around at different speeds depending upon temperature The faster they move, the higher the kinetic energy, the higher the temperature The faster they move, the higher the kinetic energy, the higher the temperature

Temperature and Kinetic Energy of Water Frozen water- low particle movement = low kinetic energy= low temperature Frozen water- low particle movement = low kinetic energy= low temperature Boiling water- high particle movement = high kinetic energy = high temperature Boiling water- high particle movement = high kinetic energy = high temperature

Measuring Temperature Thermometers are used to measure temperature Thermometers are used to measure temperature Most contain alcohol or mercury because they remain liquids at most temperature Most contain alcohol or mercury because they remain liquids at most temperature Thermometers- measure thermal expansion of a substance Thermometers- measure thermal expansion of a substance Thermal expansion- how fast a substance increases its volume because of particle movement Thermal expansion- how fast a substance increases its volume because of particle movement

Temperature Scales Fahrenheit- used in the United States Fahrenheit- used in the United States Water freezes- 32° Water freezes- 32° Water boils- 212° Water boils- 212° Body temp- 98.6° Body temp- 98.6° Celsius- used around the world and in science Celsius- used around the world and in science Water freezes- 0° Water freezes- 0° Water boils- 100° Water boils- 100° Body temp.- 37° Body temp.- 37°

Temperature Scales Kelvin- primarily used in astronomy Kelvin- primarily used in astronomy Absolute zero- all particle movement stops at 0 K Absolute zero- all particle movement stops at 0 K Approx- -459° F Approx- -459° F Never been achieved naturally or artificially Never been achieved naturally or artificially

Thermal Expansion Most materials expand when they are heated Most materials expand when they are heated Most materials contract when they are cooled Most materials contract when they are cooled This is due to the speed of the particles in the materials This is due to the speed of the particles in the materials Think of freezing and boiling water Think of freezing and boiling water

Thermal Expansion Roads are built with expansion joints- so that roads and bridges have room to expand when it gets hot Roads are built with expansion joints- so that roads and bridges have room to expand when it gets hot

Thermal Expansion of Gases Hot air rises, cold air sinks Hot air rises, cold air sinks Attic and basement during summer Attic and basement during summer Hot air balloons Hot air balloons

Heat Heat- the amount of energy transferred between two objects that are at different temperatures Heat- the amount of energy transferred between two objects that are at different temperatures Thermal energy is always transferred from the object with a higher temperature to an object with a lower temperature Thermal energy is always transferred from the object with a higher temperature to an object with a lower temperature Stethoscope- energy is transferred from your back (37) to the stethoscope (20) Stethoscope- energy is transferred from your back (37) to the stethoscope (20)

Transfer of Thermal Energy Remember energy can neither be created nor destroyed Remember energy can neither be created nor destroyed Thermal Energy is transferred in three ways Thermal Energy is transferred in three ways Conduction Conduction Convection Convection Radiation Radiation

Conduction Conduction- the transfer of thermal energy between materials that are touching Conduction- the transfer of thermal energy between materials that are touching

Conductors and Insulators Thermal conductors- substances that conduct thermal energy very well Most metals are conductors- heat up quickly Thermal insulators- substances that do not conduct thermal energy very well- heat up slower Wood, plastic, cloth Wood, plastic, cloth

Convection Convection- the transfer of thermal energy by the circulation or movement of a liquid or gas Convection- the transfer of thermal energy by the circulation or movement of a liquid or gas Convection causes some ocean currents, the movement of magma below the Earth’s surface and wind Convection causes some ocean currents, the movement of magma below the Earth’s surface and wind

Radiation Radiation- the transfer of thermal energy through electromagnetic waves like visible light and infrared waves Radiation- the transfer of thermal energy through electromagnetic waves like visible light and infrared waves Can occur through particles of matter or through space Can occur through particles of matter or through space

Heat Transfer