ANSWERS 



TO THE PEACTICAL QUESTIONS 



m THE 



FOURTEEN WEEKS COURSE 



IN 



NATURAL PHILOSOPHY. 



|.The bold-faced figures refer to the pages of the Philosophy ; the others to 

 the number of th. Practical Questions.] 



INERTIA. 



26. I. If one is riding rapidly, in which direction will he 

 be thrown when the horse is suddenly stopped ? 



In the same direction in which he is going. He has the 

 motion of the carriage, and his inertia carries him forward. 



2. When standing in a boat, why, as it starts, are we thrown 

 backward ? 



Because the inertia of our bodies keeps them stationary, 

 while the boat carries our feet forward. 



3. When carrying a cup of tea, if we move or stop quickly, 

 why is the liquid liable to spill? 



The inertia of the tea tends to keep it still or in motion, as 

 the case may be. If we move the cup quickly, the motion is 

 not imparted to the liquid soon enough to overcome the 

 inertia. When, therefore, we start, the tea spills out back- 

 ward; or, when we stop, it spills out forward. We under- 

 stand this if we can tell why a cup of tea is more liable to spill 

 than one of sugar. 



