SCIENCE OF COMMON THINGS. 



Illustrations of centrifugal force. Revolution of the earth. 



133 Can almost all revolving bodies be broken by sufficient rotative 

 velocity ? 



Yes; for the centrifugal force increases with the 

 rapidity of revolution, and finally becomes too strong 

 to be resisted by the cohesive force which binds the 

 particles of the body together. 



13Q When a vessel containing water is whirkd 

 rapidly round, why does not the water fall out when the 

 vessel is upside down ? 



Because the centrifugal force, tending 

 to make the water fly from the centre, 

 overcomes or balances the attraction of 

 gravitation, which tends to cause the 

 water to fall out. 



In Fig. 6. the water contained in the bucket which 

 is upside down, has no support under it, and if the 

 bucket were kept still in its inverted position for a 

 single moment the water would fall out by its own 

 weight, or, in other words, by the attraction of gravi- 

 tation : but the centrifugal force, which is caused by 

 the whirling of the bucket in the direction of the 

 arrow, tends to drive the water out through the bot- 

 tom and side of the vessel, and as this last force is 

 equal to and balances the other, the water retains its 

 place, and not a drop is spilled. 



How much faster would the earth be required 

 to revolve in order to make the centrifugal force equal to 

 the attraction of gravitation f 



/Seventeen times faster, or in eighty- 

 four minutes, instead of twenty-four 

 hours : in this case all bodies at the 

 equator of the earth would be destitute 

 of weight. 



141 What would be the consequence if the earth 

 revolved around its axis in less time than eighty-four 

 minutes ? 



I Gravitation would be completely over- 

 _ powered, and all fluids and loose sub- 

 Fi 6 - stances would fly from the surface. 



143 Why does a man or horse, in turning a corner rapidly, incline 

 inwards, or kan towards the corner t 



Because the centrifugal force, produced by turning 



