QUESTIONS 95 



of refrigerators. Fireless cookers, thermos bottles, revolving 

 doors, refrigerators, etc., are devices to prevent rapid trans- 

 ference of heat. 



QUESTIONS 



When we say a body possesses energy, what do we mean ? Give 

 an example of each of the two kinds of energy. 



You have used a great deal of energy to-day. Where did this 

 energy come from ? 



What is the Law of the Conservation of Energy? What do we 

 mean when we speak of "lost energy"? 



Where have you seen the effects of expansion due to heat? 



Explain the difference between mass, volume, density, and 

 weight. 



What is meant by saying that a substance is hot? 



Why are iron and type-metal better suited for casting than 

 copper and zinc? 



Describe three ways of producing heat. 



How are fires started? 



What are the conditions necessary for obtaining all the heat 

 possible from fuel ? 



Describe the different means you would employ in putting out 

 fire. 



France uses the Centigrade thermometer scale. If the tempera- 

 ture of Paris is reported as 25 C., what would the corresponding 

 temperature be in the thermometer scale generally used in the 

 United States? 



Ponds near the Great Lakes freeze entirely over. Why do not 

 the Great Lakes freeze ? 



Why would it not be as well to put ten pounds of ice-cold water 

 into the refrigerator as ten pounds of ice? 



In what ways is heat transferred? 



Describe how you would prepare from the ordinary materials 

 you have at hand a crude, inexpensive, fireless cooker. 



