IN PHYSICS. 203 



before, but with double its former velocity. What would 

 become of the other half? 



One half will go forward with a double velocity 

 (=1000 feet per sec.), and the other half will be checked 

 and will fall directly to the ground. 



(See Stewart's Physics, p. 37.) 



45 . Which would have the greater penetrating power, a 

 small cannon-ball with a high velocity, or a large one with 

 a low velocity ? 



The former would penetrate, while the latter would 

 crush an obstacle. 



46. There is a story told of a man who erected a huge 

 pair of bellows in the stern of his pleasure-boat, that he 

 might always have a fair wind. On trial, the plan failed. 

 In which direction should he have turned the bellows ? 



(See Key, p. 20.) 



47. If a man and a boy were riding in a wagon, and, 

 on coming to the foot of a hill, the man should take up the 

 boy in his arms, would that help the horse ? 



No change would be produced in the weight of the 

 entire establishment drawn by the horse, as no readjust- 

 ment of the load would modify the attraction of gravity 

 which produces the weight. Also, action =: reaction ; so 

 the man would press down on the wagon an amount 

 equal to the weight of the boy. 



48. Why does a bird, as it begins to fly, always, if pos- 

 sible, turn toward the wind ? 



For the same reason that a boy, wishing to raise a kite, 

 runs against the wind. The greater the velocity of the 

 wind, within certain limits, the greater the lifting force. 



(See note, p. 32.) 



