Thermal Energy and Heat Ch 13 in our textbook

Thermal energy and heat Heat is energy flowing between 2 objects because there is a difference in temperature. Heat is energy flowing between 2 objects because there is a difference in temperature. A calorie is defined as the amount of heat that raises one gram of water by 1 degree celsius. A calorie is defined as the amount of heat that raises one gram of water by 1 degree celsius.

Thermal energy and Heat In the 1800’s Joule did experiments to show that mechanical energy (potential energy of falling mass) could be converted in thermal energy (heat) of a jar of water. In the 1800’s Joule did experiments to show that mechanical energy (potential energy of falling mass) could be converted in thermal energy (heat) of a jar of water.

Thermal energy and heat Temperature is a property of an object. Temperature is a property of an object. Temperature tells us the atomic kinetic energy of an object. Temperature tells us the atomic kinetic energy of an object. When there is a temperature difference between 2 objects in contact heat always flows from hot to cold. When there is a temperature difference between 2 objects in contact heat always flows from hot to cold. A swimming pool and a cup of water can be at the same temperature but store very different amounts of heat (think of how much ice each can “melt”.) A swimming pool and a cup of water can be at the same temperature but store very different amounts of heat (think of how much ice each can “melt”.)

Thermal Energy and heat Specific Heat: this is a property of a material which tells you how quickly it will change its temperature when heat is added to it. For example, air will change temperature much faster than water when the same amount of heat is added to both. Specific Heat: this is a property of a material which tells you how quickly it will change its temperature when heat is added to it. For example, air will change temperature much faster than water when the same amount of heat is added to both. Specific heat of water = 4186 J/kg K Specific heat of water = 4186 J/kg K Specific heat of ice = 2090 Specific heat of ice = 2090 Specific heat of air = 1000 Specific heat of air = 1000

Thermal Energy and heat Change of state: when objects change their state (like ice melting to water) there is heat required to do this. Change of state: when objects change their state (like ice melting to water) there is heat required to do this. When objects change their state heat is added and the temperature of the object doesn’t change until all the material has changed to the new state. When objects change their state heat is added and the temperature of the object doesn’t change until all the material has changed to the new state. The heat required to change the state is called the Latent heat The heat required to change the state is called the Latent heat Latent heat of vaporization is from liquid to gas. Latent heat of vaporization is from liquid to gas. Latent heat of fusion is liquid to solid. Latent heat of fusion is liquid to solid.

Ways of transferring heat Conduction: heat flowing through a material. Conduction: heat flowing through a material. Conduction: example is heating a metal frying pan, heat is transferred through the metal as it conducts. Conduction: example is heating a metal frying pan, heat is transferred through the metal as it conducts.

Ways of transferring heat Convection: heat transferred by the motion of a fluid. Convection: heat transferred by the motion of a fluid. A convection oven moves hot air around to convect heat. A convection oven moves hot air around to convect heat.

Ways of transferring heat Radiation: Heat travelling through a vacuum. Radiation: Heat travelling through a vacuum. Heat is radiated from hot objects, this is like the heat you feel from a campfire, it’s radiated through the still air. Heat is radiated from hot objects, this is like the heat you feel from a campfire, it’s radiated through the still air.