1. A crane consists of what simple machines?

2. Name a number of "twisting tools and appliances" such as are used in placing a nut in position. Notice the manner in which they are used. Are two distinct circumferences made in their operation? Name the mechanical principles involved.

3. Name a number of "screw tools and appliances," that is, tools and appliances that are based on a spiral groove. Divide them into two parts: those that communicate motion and those that are used as fastening agents.

4. Explain the manner in which a screw communicates motion.

5. Name a number of "hoisting tools and devices." How do they work? What is the mechanical principle involved?

6. Name a number of "cutting tools." What is the shape of the cutting edge? Does the part that "cuts" come to a point or sharp edge? Does the part away from the cutting edge become thinner or thicker?

7. Name a number of "run appliances," that is, appliances or tools connecting two floors or stagings at different levels.

8. Is the "run" appliance always longer than the perpendicular distance between the two levels?

9. Divide all the ordinary tools and appliances that you remember into the following groups: hitting tools; twisting tools; screw tools; hoisting tools; cutting tools; "run" appliances.

10. Name a list of simple tools and appliances and state whether "speed" or "power" is gained by the use.

11. Name some machines that involve more than one of the simple machines or mechanical principles.

12. What is the meaning of the expression "mechanical efficiency"? "Mechanical advantage"?

13. What is friction?

14. Where is friction found?

15. Is friction a form of energy?

16. Is friction a "necessary evil" or has it some advantage?

17. Do we use friction in walking?

18. Is friction used in the case of automobiles?

19. How is friction reduced?

20. What are roller bearings? Are they useful in reducing friction?

21. Why is sand placed on the railway track?

22. Why are roller bearings placed on skates?

23. Explain why it is difficult to walk on ice.

24. What is the object of waxing a floor before dancing?

25. Give the approximate percentage of efficiency of the different simple machines.

26. What is a lubricant?

27. What are some of the dangers of excessive friction among woody materials, paper, or cotton stock?

Problems

1. A plank 11 ft. long is used to raise a barrel of flour (196 lbs.) into a car 3 1/2 ft. high. What force is necessary to raise it?

2. A carpenter uses a force of 10 lbs. in pulling a saw across a piece of wood and 100 strokes of 2 ft. each to saw the wood in two. What amount of work was done?

3. A differential pulley has a large wheel 10 in. in diameter and a small one 8 in. What is the mechanical advantage?

4. A person desires to roll a barrel weighing 200 lbs. into a wagon that is 4 ft. above the ground. What is the most effective way to do it if he can push with a force of 80 lbs.? How long a plank will be necessary?