1. - Review heat capacity and how it relates to thermal energy - Study how different materials affect the transfer of thermal energy TODAY’S OUTCOMES: HEAT Reminder: Course Evaluation Window Is Open until Dec. 7th http://mercury.pa.uky.edu/~evaluation/

2. If a thermometer is at a steady temperature, it is in thermal equilibrium with its surroundings. 8. The wind certainly makes you feel cold. Yet a fan blowing on a thermometer does not change the reading! (See for yourself! It has been set up at the front of the room). Even though both thermometers and people have red noses, they differ in the effect that the wind has on them. Discuss the other respects in which you differ from a thermometer that that might explain this. A human, being warm-blooded, is not in thermal equilibrium with its surroundings. When wind blows, it carries thermal energy with it! Wind blowing against your body speeds up the rate at which your body transfers thermal energy to its surroundings. A thermometer, being in thermal equilibrium, isn’t transferring thermal energy to its surroundings, so there is not transfer of energy to “speed up” - the temperature stays the same.

3. “Hot” = about 50°C; room temperature is about 20°C, so the change in temperature is about 30°C. 9. Dana likes to take long showers. Her mom complains that this uses up all the hot water. “Heating water is expensive” she says. A) If the tank holds 200 kg of water, how much energy is needed to make it “hot”? B) Electricity costs about 10¢ per kilowatt-hour (which is 3,600,000 Joules). How much does Dana’s shower cost? Total energy = 836800 Joules/°C ✕ 30°C = 25,104,000 Joules Energy used/°C = 4184 Joules/kg/°C ✕ 200 kg = 836800 Joules/°C energy = 25,104,000/3,600,000 kilowatt-hours = 6.97 kilowatt-hours at 10¢ per kilowatt-hour, this is just under 70¢.

4. HEAT CAPACITY The heat capacity of a material is the amount of energy required to raise 1 kg by 1°C. Heat capacity of water = 4184 Joules/kg/°C Heat capacity of aluminum = 897 Joules/kg/°C Water has a much higher heat capacity than aluminum. 1 kg of water can hold much more thermal energy than 1 kg of aluminum!

5. HEAT CAPACITY An equation you need to know how to use: Thermal energy = mass ✕ heat capacity ✕ temperature change ( If you took high school chemistry, you might have seen this written as Q = mc∆T ) thermal energy (like kinetic and potential energy) is measured in joules

6. Thermal energy contains a lot of joules: from the Unit on Force and Motion: 1 joule is the amount of energy needed to lift a 1 kg mass 1 meter high 1 m 1 kg 1 liter of water has a mass of 1 kg It takes over 4000 joules to raise the temperature of 1 liter of water by 1°C!

7. - The definition of heat capacity - What a differing heat capacity means for the amount of thermal energy stored in a material - How to use heat capacity to calculate the amount of thermal energy transferred WHAT YOU ARE EXPECTED TO KNOW:

8. - Review heat capacity and how it relates to thermal energy ✓ - Study how different materials affect the transfer of thermal energy TODAY’S OUTCOMES: HEAT Reminder: Course Evaluation Window Is Open until Dec. 7th http://mercury.pa.uky.edu/~evaluation/