66 Common Science 



Inference Exercise 

 Explain the following : 



71. When you turn on the faucet of a distilled- water bottle, 



bubbles go up through the water as the water pours out. 



72. A clothes wringer has a long handle. It wrings the clothes 



drier than you can wring them by hand. 



73. You use a crowbar when you want to raise a heavy object 



such as a rock. 



74. Sometimes it is almost impossible to get the top from a jar of 



canned fruit unless you let a little air under the edge of the 

 lid. 



75. It is much easier to carry a carpet sweeper if you take hold 



near the sweeper part than it is if you take hold at the end 

 of the handle. 



76. You can make marks on a paper by rubbing a pencil across it. 



77. A motorman sands the track when he wishes to stop the car on 



a hill. 



78. On a faucet there is a handle with which to turn it. 



79. Before we pull candy we butter our fingers. 



80. You can scratch glass with very hard steel but not with wood. 



SECTION n. Inertia. 



Why is it that if you push a miniature auto rapidly, it will 

 go straight? 



Why does the earth never stop moving? 



When you jerk a piece of paper from under an inkwell, 

 why does the inkwell stay still? 



When you are riding in a car and the car stops sud- 

 denly, you are thrown forward ; your body tends to 

 keep moving in the direction in which the car was going. 

 When a car starts suddenly, you are thrown backward ; 

 your body tends to stay where it was before the car 

 started. 



When an automobile bumps into anything, the people 

 in the front seat are often thrown forward through the 

 wind shield and are badly cut ; their bodies keep on 



