PHYSICS 3200: Heat, Light and Sound

Finish reading Chapter 17 and skim chapter 18

Start reading chapter 19 on Vibrations and Waves by Monday, April 21.

Homework Assignment 6: Due Wednesday, April 23

1. Do all the molecules in a liquid, e.g. water, at a constant temperature have the same kinetic energy? Explain your answer.

2. What is evaporation and why is it a cooling process? Exactly what cools?

3. Why would warm water evaporate more readily than cold water?

4. What is condensation, and why is it a warming process? Just what warms?

5. Which will be more damaging, being burned by steam at 100^oC or by liquid water at 100^oC? Why?

6. Why do you feel warmer on a hot humid day than on a hot dry day?

7. Does a solid give off or absorb energy when it turns into a liquid?

8. Why would a liquid absorb energy when it turns into a gas? (Where does the absorbed energy go?)

9. If you stand around the swimming pool on a cool, dry day, it doesn’t feel as cold just before you get into the water, i.e. when you are dry, as it does when you get out, i.e. when you are wet. Why might that be so?

10. When we say that heat flows from warm objects to cooler objects, is that always true? Can we transfer heat from a cool object to a warm one? If so, give an example.

11. I am generating electricity by heating water to produce steam and using the steam to turn a turbine. The temperature of the steam is 550^oC before it reaches the turbine. After going through the turbine, it’s temperature is 110^oC. What is the maximum efficiency I can get out of this type of “steam engine”?

I’m planning to have an Exam covering chapters 15-18 soon, Possibly on Monday, April 28

Proposed formulas are on the reverse side of the page

Proposed formulas

Change in Position = Final position – Initial position		1N = 1kgm/s^2
		F = Ma
Weight = Mg	g = 10m/s^2	Work = ± Fd
	Gravitational PE = Mgy or Mgh	E = KE + PE
		Work = Change in KE
1J = 1Nm = 1 kg m^2/s^2	Workother = Change in Energy

T_Kelvin = T_centigrade + 273