1. When is a body hot?

2. When metals begin to melt, they liquefy at once. Why?

3. Why is ice packed in sawdust?

4. Why does a draft extinguish a flame?

5. Which will heat more quickly, rough or polished surfaces?

6. Why does sprinkling a shop floor cool the air?

7. Why are steam cylinders polished on the inside?

8. Why are glass tumblers broken by pouring hot water into them?

9. What is the basis of all cooling mixtures?

10. Explain why so much energy is lost in steam engines.

11. Is temperature a measure of the amount of heat in a body?

12. Explain why railroad engines have a polished sheet iron jacket around the cylinder and boiler.

13. What becomes of the cloud which forms about a blowing locomotive whistle?

14. Why are expansion joints added to long lines of steam pipes?

15. Place a ball through a ring, then heat the ball in an alcohol or Bunsen flame and try to pull it back through the ring.

16. Why do mechanics who work in a warm room wear flannel shirts to keep cool in the summer and warm in the winter?

17. Why is felt a better conductor of heat when firmly packed than when loosely packed?

18. Ducts and pipes are frequently covered with felt or asbestos. Why?

### Problems

3. How many units (B.T.U.) will be required to raise 4863 lbs. of water 62° F.?

4. How many units (B.T.U.) will be required to raise 785 lbs. of water from 74° F. to 298° F.?

5. How many units of heat will be necessary to raise 40 g. from 50° C. to 70° C?

6. A wrought iron bar 22 ft. long is heated from 70° F. to 300° F. How much will it lengthen?

7. A straight pipe 256 ft. long is heated from a temperature of 50° F., to a temperature of 370° F. How much will the pipe expand? How much would a brass pipe expand under the same conditions? (Coefficient of expansion of brass is .00001052. Coefficient expansion of iron is .0000065 ft. per foot of length per degree Fahrenheit.)

8. A bar of copper 12 ft. 6 in. long at 82° F. is heated to 289° F. What is its length while it is at 289° F.?

9. A brass rod measuring 36 ft. 3 in. at 78° is heated to 188° F. What is its greatest length?

10. A flat surface of zinc measuring 4 ft. 6 in. is heated from 81° F. to 312° F. How much does the surface expand?