Heat and Temperature
Energy that makes things hot!
Outline
•	Review of Principle of Conservation of Energy.
•	Temperature and Thermal Equilibrium.
•	Heat Capacity
•	Thermal Expansion
•	Temperature Measurements

Conservation of Energy
•	E total = Ek + EP
•	Energy conversions: The Faith Pendulum.
•	Hydroelectric Power
•	EP            work turning a turbine.
•	Wind Power
•	Ek                   work turning the rotor blades.
•	Heat Power
•	?               Work turning the fan
Thermal Equilibrium
•	Hot chili and cold coke example
•	Definition:
•	Heat is what flows between two objects when there is a difference in temperature.
•	Heat flows from the higher temperature to the lower temperature, so that the higher temperature falls, and the lower temp. rises!
•	Heat flows until the two temperatures are the same, and then it stops.

Heat and Temperature
•	Heat = Q (units?)
•	Temperature = T (degrees C for now)
•	Heat Capacity = c:
•	Q = c m ÄT
•	“Heat” = “Heat Capacity” times “mass” times “change in Temperature”
•	Answers the question: How much heat must I add to raise or lower the temperature?
Heat Capacity demonstrations
•	Heating a wax paper cup
•	Heating a wax paper cup with water
•	Heating a balloon
•	Heating a balloon with water
•	Which cools off first?  The aluminum pan or the cheese on the pizza?

Heat Units
•	A calorie: the amount of heat needed to raise 1 gram of water from 14.5 C to 15.5 C
•	So, c = 1 cal/g-C
•	A Btu (British thermal unit): the amount of heat needed to raise 1 pound of water from 63 to 64 F.
•	Then c = 1 Btu/lb-F
•	A Food calorie is 1 kilocalorie or 1,000 calories.
•	Heat is energy! 
•	1 calorie = 4.18 Joules; 1 Btu = 1055 Joules.

Heat Capacity examples
•	Heat capacity of water c = 1 cal/g-C; of gold, c = .03 cal/g-C.
•	How much heat is needed to raise the temperature of 100 g of water 10 C?
•	Q = 1cal/g-C x 100 g x 10 C = 1,000 cal
•	How much heat needs to be released to raise the temperature of 100g of gold by 10 C?
•	Q = .03cal/g-C x 100 g x 10 C = 30 cal
Thermal Equilibrium
•	Two objects at different temperatures are placed together.
•	By energy conservation – Q lost by the hotter one must equal Q gained by the lower one.
•	The final temperature of the two objects will be the same.
•	The ratio of heat capacities (and masses) tells the relative temperature change.
•	For equal masses of gold and water: c water / c gold = 1 / .03 = 33 --- gold will change in temperature 33 times as much as the water.