22 MATTER AND ENERGY 



Specific gravity is the weight of a substance compared 

 with the weight of an equal volume of water. The 

 specific gravity of water is 1 ; of cork, 0.2 ; of ice, 0.9 ; 

 of iron, 7.2 ; of lead, 11.4 ; of mercury, 13.6 ; of gold, 

 19.4 ; of glass, 3.4 ; and of platinum, 21.2. 



QUESTIONS 



1. Name some examples of the effect of gravitation. 



2. What is meant by gravity? Is it any different from 

 gravitation ? 



3. Name some effects of gravity. If there were no such force, 

 would bodies fall to the ground ? Why could we not walk if there 

 were no such force ? 



4. Upon what two things does the strength of gravitation 

 depend ? Would the moon attract a body more or less than the 

 earth, that is, would a body weigh more on the moon or on 

 the earth? If we were on the moon, could we jump higher than 

 we can on earth? 



5. Define weight. Explain how weight gives us an idea of the 

 amount of matter in a body. 



6. What is specific gravity ? Does it depend upon the kind of 

 matter or upon the size of the body? Would a lump of gold 

 weigh more or less than the same volume of lead? 



