EXAMPLES. 295 



6. If a small hole be made in the top of a diving bell, 

 will the water flow in or the air flow out ? 



7. If a cylindrical diving bell, height 5 feet, be let down 

 till the depth of its top is 55 feet, find (1) the space 

 occupied by the air, and (2) the volume of air that must be 

 forced in to expel the water completely, the water barometer 

 standing at 33 feet. 



Ans. (1) 1.8 nearly ; (2) f^ths of the volume of the bell. 



8. The weight of a diving bell is 1120 Ibs., and the 

 weight of the water it would contain is 672 Ibs. Find the 

 tension of the rope when the level of the water inside the 

 bell is 17 feet below the surface (h = 33 feet). 



Ans. 676.48 Ibs. 



9. A cylindrical diving bell of height a is sunk in water 

 till it becomes half full. Show that the depth from the 



surface of the water to the top of the bell is h - 



<c 



10. A cylindrical diving bell, of which the height inside 

 is 8 ft., is sunk till its top is 70 feet below the surface of the 

 water. Find the depth of the air space inside the bell 

 (h = 33 feet). Ans. 2 feet. 



11. (1) Describe the action of a common pump ; (2) 

 distinguish between a lifting pump and a forcing pump ; 

 (3) to what height could mercury be raised by a pump? 



12. The length of the lower pipe of a common pump 

 above the surface of the water is 10 feet, and the area of 

 the upper pipe is 4 times that of the lower ; prove that if 

 at the end of the first stroke the water just rises into the 

 upper pipe, the length of the stroke must be 3 feet 7 inches 

 very nearly (h = 33 feet). 



13. If the diameter of the piston be 3 inches, and if the 

 height of the water in the pump be 20 feet above the well, 

 what is the pressure on the piston ? Ans. 61.3 log. 



