Chapter+10+Thermal+Physics

Chapter 10 - Thermal Physics by.... Jon Blinn!

Thermal Physics is the study of temperature, heat, and how they affect matter. Vocabulary:
 * Thermal contact** - two objects are in thermal contact if energy can be exchanged between them
 * Thermal equilibrium** - two objects are in thermal equilibrium if they are in thermal contact and there is no not exchange of energy
 * Heat** - The exchange of energy between two objects because of differences in their temperatures
 * Thermometer** - a device calibrated to measure the temperature of an object
 * Zeroth law of thermodynamics (law of equilibrium)** - If objects A and B are separately in thermal equilibrium with a third object C, then A and B are in thermal equilibrium with each other. In other words, if A = C and B = C, then A = B. Simple!
 * Temperature** - the property that determines whether or not an object is in thermal equilibrium with other objects - remember, two objects that are in thermal equilibrium with each other are at the same temperature!
 * Celsius, Kelvin, Fahrenheit** - Temperature scales
 * SI Unit of Temperature** - Kelvin!

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VITAL FORMULAS FOR PHYSICS Note: values for R can be 8.31 J/mol*K or 0.0821 L*atm/mol*k

Time for some EXAMPLE PROBLEMS

1. Convert 85.23 degrees Celsius to Fahrenheit. Solution: (9/5)*85.23+32 = Fahrenheit = 185.41 degrees Fahrenheit

2. Convert 94 degrees Fahrenheit to Celsius. Solution: (5/9)(94-32) = Celsius = 34.44 degrees Celsius

3. Convert 45.6 degrees Celsius to kelvin. Solution: 45.6 + 273.15 = 318.75 degrees kelvin

4. A steel railroad track as a length of 30 meters when it is 0 degrees Celsius. What is the length on a hot day of 40 degrees Celsius? Note: The coefficient of steel is 11 x 6 -6 ( o C) Solution: L=11 x 6 -6 ( o C) * (30.0m) * (40 - 0) = 30.013m

5. Find the change in volume of the Earth's oceans due to an average temperature change of 1 o C. Note: The coefficient of volume of water is 2.07 x 10 -4

Solution: Using our change in volume formula, V = BV o T. V/Vo= BT = 2.07 x 10 -4 *1( o C) = 0.0002

6. An ideal gas at 20 degrees Celsius and a pressure of 1.5 x 10 5 Pa is in a container having a volume of 1.00L. Determine the number of moles of gas in this container.

Solution: Using PV = nRT, solve for n. n = (PV)/(RT) =(1.5 x 10 5 Pa * 1 x 10 -3 m 3 )/(8.31 * 293K) = 6.16 x 10 -2 mol Note: convert temperature to KELVIN or your answer will be WRONG! Also, memorize the values for R listed earlier.

QUIZ TIME!

1. What is 40 degrees Fahrenheit converted to kelvin? A. 4.44 B. 277.594* C. 377.15 D. 263.37

2. What is the SI unit of temperature? A. Fahrenheit B. Celsius C. Kelvin* D. Thermos

3. If you have a gas sealed in a 2 liter bottle with a pressure of 2 atmospheres at a temperature of 206 o K, how many moles of gas do you have? A. 0.237 moles* B. 0.0023 moles C. 0 moles D. 0.432 moles

4. For some strange reason, you find a person measuring everything outside when it is 0 o C. Being the genius that you are, you ask him to measure the length of your steel cane. When he tells you that it is 1.3 meters long, you want to know what it will expand to on a blistering 80 o C day. After checking your notebook in your back left pocket of your blue jeans, you see that the coefficient of steel is11 x 6 -6 ( o C). So tell me, what is the new length of your steel cane? A. 1.416 meters B. 1.331 meters C. 1.294 meters D. 1.301 meters*

5. You are riding a horse in the middle of the woods. After accidentally riding off a cliff, you land mysteriously in a gigantic lake of water. You take out your handy dandy thermometer and record that the temperature is 20 o C. All of a sudden you hear a loud engine start. The water begins to rise so you swim to shore. When you make it onto dry land safely, you see a sign that reads "warning: lake may get hot." By the time you are out, you stick the thermometer back in and see that the lake has risen to 99 o C in a matter of minutes. How much has the water expanded if the original volume was 1,000L? The coefficient of water is 2.07 x 10 -4. A. 10.2L B. 16.4L* C. 20.5L D. 13.8L

Congratulations! You now know how to do everything possible relating to thermal physics! Well, at least as much as a monkey is able to do....