Notes

ESL
Page 164
Exs 13,15,23,31
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As a class, what are some things you have to do after class today?
Before going to bed tonight, what do you have to do? Is there any place you have to go later today?
In everyday life, what are some things that you must have in order to survive?
Looking ahead to the next week, what are some things that you have to do?
Last week, what were some things that you had to do?
In the job of a doctor, what kinds of things must they know about? What are some tasks that a doctor has to do on a daily basis?

Physics
Heat
kinetic molecular theory

- All matter is made up of small constantly moving particles
- Particles exerts force on each other and are on average far apart (relative their diameter)
- The three states of matter are due to the distance b/w particles and the strength of the force of attraction b/w them

Heat -> Thermal energy transfer

- Thermal energy: the total energy (potential and kinetic) of all particles in a object
- Heat: energy that is transferred from one body to another because of a difference in temperature
- Temperature: a measure of the average kinetic energy of individual particles

Temperature Scales

- Temperature: measure of average kinetic energy of the particles in a substance
- Celsius Scale - based on boiling point (100°) and freezing point (0°) of water
- Fahrenheit scale - based on boiling point freezing point of salt-water °c temp = °f temp -32) * 5/9
-Kelvin Scale - based on absolute zero (no motion in the particles of a substance)

Absolute Zero & the kelvin Scale

- The Kelvin scale is setup so that its zero point is the coldest possible temperature absolute zero, at which point a substance would have zero internal energy. This is 273.15 °C, or -459.69 °F. Absolute zero can never be reached, but there is no limit to how close we can get to it. Scientists have cooled substances to within 10-5 kelvins of absolute zero. How do we know how cold absolute zero is, if nothing has ever been at that temperature? The answer is by graphing Pressure vs. Temperature for a variety of gases and extrapolating.

Thermal Equilibrium

Two bodies are said to be at thermal equilibrium if they are at the same temperature. This means there is no net exchange of thermal energy b/w the two bodies. The top pair of objects are in contact, but since they are at different temps, they are not in thermal equilibrium, and energy is flowing from the hot side to the cold side.

HOT ---heat ---> cold
26 °C 26 °C
no heat flow

Methods of heat transfer
Methods of heat transfer: conduction, convection, radiation.
Convection
-Heat is transferred by the circulation of a fluid (liquid or gas) over relatively large distances