Читать книгу Physics - Willis E. Tower - Страница 38

1. Where have you seen an air cushion? Describe it and its use.

2. Where have you seen an hydraulic press? Why and how used?

3. Where have you seen hydraulic elevators? What moves them?

4. Where do you know of liquids under pressure? Three examples.

5. What is the pressure in water at a depth of 1500 cm. Express in grams per square centimeter and in kilograms per square centimeter.

6. What head[C] of water is required to give a pressure of 200 g. per square centimeter? 2 kg. per square centimeter?

7. What pressure will be produced by a "head" of water of 20 meters?

8. If 1728 cu. in. of water are placed in a vertical tube 1 sq. in. in cross section to what height would the water rise? It would give how many feet of head?

9. What would the water in problem 8 weigh? What pressure would it produce at the bottom, in pounds per square inch? From this, compute how many feet of "head" of water will produce a pressure of 1 lb. per square inch.

10. Using the result in problem 9, what "head" of water will produce a pressure of 10 lbs. per square inch? 100 lbs. per square inch?

11. From the result in 9, 100 ft. of "head" of water will produce what pressure? 1000 ft. of "head?"

12. If the diameter of the pump piston in a hydraulic press is 2 cm. and that of the press piston 50 cm. what will be the force against the latter if the former is pushed down with a force of 40 kg.?