' THE EEASON WHY. }97 



. 



" Children obey your parents in all things : for this is well-pleasing unto the 

 Lord." COLOSSIANS in. 



the surface from which it was propelled ; this line is the tangent U 

 the circle of the hoop ; and the tendency of all the parts of the 

 hoop to fly off in this manner, counteracts the attraction of the 

 earth, so long as the hoop is kept in motion. 



862. Why does the hoop, in falling, make several side 

 revolutions ? 



Because its onward movement, not being quite expended, in- 

 fluences the centre of gravity of the hoop, and changes its line of 

 direction. The hoop is also elastic, and when its sides strike the 

 earth, they spring up again, and continue turning until the 

 opposing forces are overcome by the attraction of gravitation. 



863. Why will a little loy balance a large boy on a 

 see-saw ? 



Because the " see-saw" may be placed so that its ends are at 

 unequal distances from the centre. This gives the little boy the 

 power of leverage, by which is meant the increase of power, or 

 weight, by mechanical means. 



Tig. 44. BOYS AND " SEE-SAW. 



864. Why does the little boy sink to the ground when the 

 larger loy slightly Icicles the earth ? 



Because the larger boy, by kicking against the earth, opposes by 

 mechanical force the attraction of gravitation acting upon him, 

 and he becomes temporarily less attracted to the earth than the 

 little boy. 



865. Why can the little loy, if he- choose, keep the ligloy 

 up, when once he is up ? 



