ANS^JKS TO PRAVT1VAL QUESTIONS 



4. Why &>,fofrlo.d$*pfr'r'sued, \cctn we. escape by dodging? 

 We turn sharply. ' O'ur pursuer, ignorant of our design, 



cannot overcome his inertia so as to turn as quickly, and 

 hence is carried past. 



5. Why is a carriage or sleigh , when sharply turning a 

 corner, liable to tip over f 



Because its inertia tends to carry it directly forward. A 

 puzzling question in this connection is Why is a sleigh more 

 liable to tip over than a wagon ? 



6. Why, if you place a card on your finger, and on top of it 

 a cent, can you snap the card from under the cent 'without 

 knocking the latter off your finger? 



Because the friction between the card and the cent is so 

 slight that, by a quick snap, you can overcome the inertia of 

 the former without imparting any force to the latter. 



7. Why } after the sails of a vessel are furled, does it still 

 continue to move; and why, after the sails are all spread, 

 does it require some time to get under full headway? 



Its inertia must be overcome in the one case by the resist- 

 ance of the air and water, and in the other by the force of the 

 wind. 



COHESION. 



4O. i . Why can we not weld a piece of copper to one of 

 iron ? 



Cohesion acts only between molecules of the same kind. 



2. Why is a bar of iron stronger than one of wood? 

 Because its force of cohesion is stronger. 



3. Why is a piece of iron, when perfectly welded, stronger 

 than before it was broken f 



By the hammering, more particles are brought within the 

 range of cohesion. 



4. Why do drops of different liquids vary in size f 

 Because they vary in cohesive force. 



5. Why, when you drop medicine, will the last few drops 

 contained in the bottle be of a larger size than the others ? 



