1. Matter and Energy

2. Drill
Identify which of the two descriptions of your class is an intensive property and which is extensive:
The number of students in the class.
The grade level of the students in class.

3. Thermodynamics - “the study of systems and energy transfer”
Matter and Energy
Thermodynamics - “the study of systems and energy transfer”
Heat (Q) – energy transfer caused by a temperature difference
If we place a flame beneath a system, we would be adding heat to it.
We could also remove heat by surrounding the system with an ice bath.

4. Matter and Energy
Heat (Q) – energy transfer caused by a temperature difference
So far, we have defined heat transfer and talked about its sign convention…
Q in is (+)
Q out is (-)
…but we haven’t talked about how heat is transferred.

5. Matter and Energy Conduction Convection Radiation
Heat (Q) – energy transfer caused by a temperature difference
Now let’s talk about the modes of heat transfer (the ways in which heat goes in/out of a system)…
Q in is (+)
Q out is (-)
Conduction
Convection
Radiation

6. Matter and Energy Why or why not? Conduction!!!
Heat (Q) – energy transfer caused by a temperature difference
This man is holding one end of a metal rod inside of a furnace with his bare hands. Do you think that he can do that for very long?
Why or why not?
Conduction!!!
Over time the rod heats up…

7. Matter and Energy
Heat (Q) – energy transfer caused by a temperature difference
Conduction Heat Transfer – energy transfer between molecules due to a temperature difference
The parts of the rod inside the furnace heat up first.
Over time, those molecules pass that heat along to the molecules near them that are outside the furnace.
Eventually the whole rod heats up!

8. Matter and Energy Computers use fans to cool down…just like us!
Heat (Q) – energy transfer caused by a temperature difference
The insides of a computer get very hot as it operates. How do we keep them from overheating?
Computers use fans to cool down…just like us!
This type of heat transfer is called Convection.

9. Matter and Energy
Heat (Q) – energy transfer caused by a temperature difference
Convection Heat Transfer – energy transfer due to the bulk motion of a fluid
As the boards and chips inside the PC heat up, the fan turns on.
The fan pulls in cool air from outside the PC which picks up the heat from the boards and chips.
The now hot air is forced out of the PC, cooling it down.

10. Matter and Energy
Heat (Q) – energy transfer caused by a temperature difference
The temperature outside changes over time; it’s cool at night and warm throughout the day. Why?
Radiant energy leaves the earth during the night, cooling the earth down (when the sun is “down”).
Radiant energy from the sun warms the earth during the day (when the sun is “up”).

11. Matter and Energy
Heat (Q) – energy transfer caused by a temperature difference
The temperature outside changes over time; it’s cool at night and warm throughout the day. Why?

12. Thermodynamics - “the study of systems and energy transfer”
Matter and Energy
Thermodynamics - “the study of systems and energy transfer”
Heat (Q) – energy transfer caused by a temperature difference
Conduction
Convection
Radiation