1. Thermodynamics

2. Thermodynamics Thermo (heat) + dynam (move) = moving heat
Thermodynamics is the study of how heat moves and what effects heat has on objects and substances.

3. Heat Transfer
Heat diffuses; it moves from hotter objects to cooler ones.
It can move in three ways: Conduction, Convection, and Radiation.

4. Conduction
If you are going to stir a pot of soup, which spoon will you use? Metal or wood?
Heat can transfer between two things that are touching or through a single object. This is called conduction.
Different substances conduct heat differently. Some are good conductors (like metals), some are poor conductors (like wood).

5. Conduction
Heat moves through an object or substance when atoms bump into each other.
If one end of an object is heated, the atoms at that end vibrate more.
As they bump into their neighbors, some of their energy is passed to the neighbors.
The neighbors then bump into their own neighbors.
This happens again and again until the temperature is the same through out the object.

6. Convection
Most things get bigger as they get hotter, but there mass does not change.
This means they become less dense as they get hotter.
If a heat source is at the bottom of a fluid, the heated molecules will float to the top, while the cooler ones sink to the bottom to be heated.

7. Convection Where is the air conditioner? Why?
The hottest air in the room is the least dense, so it floats to the ceiling.
The air conditioner takes it in, cools it, then blows it back out.
This cool air is more dense than the air in the room and sinks to the floor.
This pushes warmer air up to the ceiling, where the air conditioner can take it in, cool it, and blow it back into the room.

8. Radiation
Heat can travel through space (or air or water) in the same way that radio waves, light, and X-rays do.
The color of an object effects the rate at which it radiates heat. Dark objects radiate (and absorb) heat more quickly than lighter objects.

9. R a d i a t i o n
We’ve all seen a rainbow. The many colors are called the visible spectrum. But there is also an invisible spectrum of “light” that is too small or too big for our eyes to see.
Infrared (below red) light is too big for us to see as light, but we can feel it as heat.
Heat that travels by itself (not through conduction or convection) is traveling as infrared radiation.

10. How many methods of heat transfer are shown below?