Temperature and Heat
Jan 20, 2016
Temperature and Heat
Temperature
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
All matter is made of atoms or molecules.
These particles move around at different speeds depending upon 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
Boiling water- high particle movement = high kinetic energy = high temperature
Measuring Temperature
Thermometers are used to measure temperature Most contain alcohol or mercury because
they remain liquids at most temperature Thermometers- measure thermal expansion
of a substance Thermal expansion- how fast a substance
increases its volume because of particle movement
Temperature Scales
Fahrenheit- used in the United States Water freezes- 32° Water boils- 212° Body temp- 98.6°
Celsius- used around the world and in science Water freezes- 0° Water boils- 100° Body temp.- 37°
Temperature Scales
Kelvin- primarily used in astronomy Absolute zero- all particle movement
stops at 0 K Approx- -459° F Never been achieved naturally or artificially
Thermal Expansion
Most materials expand when they are heated
Most materials contract when they are cooled This is due to the speed of the particles
in the materials 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
Thermal Expansion of Gases
Hot air rises, cold air sinks Attic and basement during summer Hot air balloons
Heat
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 Stethoscope- energy is transferred from
your back (37) to the stethoscope (20)
Transfer of Thermal Energy
Remember energy can neither be created nor destroyed
Thermal Energy is transferred in three ways Conduction Convection Radiation
Conduction
Conduction- the transfer of thermal energy between materials that are touching
Conductors and Insulators
Thermal conductors- substances that conduct thermal energy very wellMost metals are conductors- heat up quickly
Thermal insulators- substances that do not conduct thermal energy very well- heat up slower
Wood, plastic, cloth
Convection
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
Radiation
Radiation- the transfer of thermal energy through electromagnetic waves like visible light and infrared waves Can occur through particles of matter or
through space
Heat Transfer