FORCE AND MOTION 



65 



800 



of that substance. One cubic centimeter of water weighs 

 one gram; therefore the density of water is one gram per 

 cubic centimeter. 



66. Methods of Finding the Density of a Solid. - 

 It is not a difficult matter to find 

 the density of a substance by 

 experiment. 



When the substance is in the 

 form of a regular solid, such as 

 a sphere, cylinder, or cube, the 

 volume can be calculated from 

 measurement of the dimensions. 

 Determine the volume by measure- 

 ment of dimensions, and the weight 

 by use of balances. Then divide 

 the number representing the weight 

 in grams by the number repre- 

 senting the volume in cubic centi- 

 meters. If a block of iron con- 

 taining 30 cubic centimeters weighs 

 234 grams, 1 cubic centimeter 

 weighs 7.8 grams. Its density, 

 then, is 7.8 grams per cubic centi- 

 meter. 



When the snbstanpp had an A , measurin 8 S lass con - 



nas an taine j 640 cu cm of water 



irregular form, its density can be A piece of stone was sus- 



400 



FIG. 27. FINDING THE 

 VOLUME .OF A SOLID 

 BY DISPLACEMENT OF 

 WATER 



1. What was the volume of 

 the stone? 2. How do you 

 know? 



found in the following way, pro- 



vided the substance will sink and 



will not dissolve in water. First 



find its weight. Then take a 



measuring glass, which has lines on the side to show the 



amount of liquid which it contains. Pour water into the 



glass, perhaps to the 200 cu. cm. line. Tie a thread about 



the body and let it down into the water. The water rises 



in the glass, because two bodies cannot occupy the same 



