IN POPULAR PHYSICS. 15 



2. Will a body weigh more in a valley than on a mount- 



It will, because the distance to the earth's center is less, 



.7. Will a pound weight fall more slowly than a two- 

 pound weight ? 



They will both fall in the same time, except the slight dif- ^ 

 ference which is caused by the resistance of the air. Galileo (^ 

 propounded this view, and proved it, in the presence of 

 nesses, by letting unequal weights fall from the leaning tower 

 of Pisa. 



4. How deep is a well 9 if it takes three seconds for a stone 

 to fall to the bottom of it ? 



S-igt 2 



S = 16 x 3- = 144 feet. 



5. Is the center of gravity always ivithin a body as, 

 for example, a pair of tongs ? 



No. It may be entirely outside, and is usually so for a pair 

 of tongs. 



6. In a ball of equal density throughout, ivhere is the 

 center of gravity ? 



At the center of the ball. 



7. Why does a ball roll down hill ? 



Because the line of direction falls without the small base of 

 the ball. 



S. Why is it easier to roll a round body than a square 

 one? 



Because the base of the ball is so much smaller, and there- 

 fore the center of gravity need not be raised to bring the line 

 of direction without. 



9. Why is it easier to tip over a load of hay than one of 

 stone ? 



Because the center of gravity in a load of hay is very high, 

 and in a load of stone very low. Therefore the center of grav- 



