Thermal Energy and Heat Thermal energy is the

Thermal Energy and Heat

Thermal energy is the sum of the potential energy and the kinetic energy possessed by the molecules of an object. n n A hot object has more thermal energy than a cold object because the molecules are moving faster. A substance in its liquid state at its boiling point has less thermal energy (per kilogram) than when it is a gas at the same temperature. http: //phet. colorado. edu/sims/friction_en. html

Review relationship between Temperature and Heat: Heat Temperature Thermal energy that is Defined…. transferred!! Measure of the average Defined…. Kinetic energy of the molecules in a substance! Does it depend on Mass? not mass Does it. Isdepend on Mass? Is mass dependent!! Cannot be measured directly!! Can you measure it? in Only by the changes temperature they cause!! dependent!! Can be youmeasuredirectly!! it? With a thermometer!! Units? ? ? Measured in o. C, o. F, or Measured in Joules(J) K Units? ? ?

Heat - The flow of thermal energy from one object to another. Thermal energy transferred from cup to hand Heat always flows from warmer to cooler objects. Thermal energy transferred from hand to ice cube

3 Ways to Transfer Heat 1. Conduction---direct contact. 2. Convection—transfer of heat in liquids and gases!! 3. Radiation—transfer through empty space!!

Discuss Heat Transfer Mechanisms!!! RADIATION CONVECTION CONDUCTION

MEASURING TEMPERATURE SI UNITS n Kelvin/Celcius K = °C + 273 e. g. 10°C = 283 K °C = K – 273 e. g. 10 K = -263°C Alternate unit (the “US” units!) n Fahrenheit °C = 5(°F – 32) 9 e. g. 75°F = 24 °C