32 ANSWERS TO PRACTICAL QUESTIONS 



A ton of gold ? 



1,000 oz. = weight of a cu. ft. of water. 



19.34 = spec. grav. of gold. 

 19,340 oz. * weight of a cu. ft. of gold. 

 32,000 oz.* -4- 19,340 oz. = 1.6, the no. of cu. ft. 



A ton of copper ? 



1,000 oz. x 8.9 = 8,900 oz. 

 32,000 oz. -f- 8,9QO oz. = 3.6 (nearly) the no. of cu. ft. 



30. WJiat is the weight of a cube of gold 4 feet on each 

 side? 



4 3 = 64, the no. of cu. ft. 



19,340 oz.* (no of oz. in 1 cu. ft.) x 64 = 77,360 Ibs. 



31. A cistern is 12 ft. Iong 9 G ft. wide, and 1O ft. deep. 

 When full of water, what is the pressure, on each side? 



On one side, 12 x 10 x 5 x 1,000 oz. = 600,000 oz. = 37,500 Ibs. 

 On one end, 6 x 10 x 5 x 1,000 oz. = 300,000 oz. = 18,750 Ibs. 



32. Why does a dead fish always float on its back ? 



It has its swimming-bladder located just under the spine ; 

 and this is the lightest part of its body, and, of course, comes 

 to the top as soon as the fish dies. 



34. A vessel holds 1O Ibs. of 'water ; how much mer- 

 cury would it contain ? 



Mercury is 13.5 times heavier than water. Hence the vessel 

 would contain 10 Ibs. x 13.5 = 135 Ibs. of mercury. 



35. A stone weighs 70 Ibs. in air and 5O in water. 

 What is its bulk ? 



70 50 = 20. 20 x 16 oz. = 320 oz., the weight of water displaced. 

 320 oz. is ^ of a cu. ft. 



* In these solutions the student should notice that avoirdupois 

 is used in weighing the gold. To be exact, 1,000 oz., the weight of a cu. 

 ft. of water, should be reduced to Troy weight, and the Ib. gold taken * 

 12 oz. Troy, when the answer would be about 1.36 cu. ft. 



