WHAT ARE THE CHARACTERISTICS OF HEAT? Ill 



smooth, light, or shiny substances. Substances which 

 absorb heat give it up easily by radiation. 



Demonstration 4. Heat Causes Expansion. 



Gas. A glass flask filled with air having a balloon attached to 

 one end is heated. What happens to the balloon? Let the flask 

 cool. Result? 



Liquid. Fill a 500 cc. flask full of colored water. Place a 

 stopper carrying a long glass tube so that the colored water rises 



in the tube. Mark the level of the water carefully on the tube. 

 Now warm the flask by placing in a dish of hot water. What 

 happens ? Remove from the hot water and allow the flask to cool. 

 Result? 



Solid. Support a copper rod or tube two or three feet long on 

 a block, as shown in the illustration. End A is not movable; 



TO* 



-move burner- 

 back Q*ul 



end B can roll over a wire bent so the end hangs vertically in front 

 of the block. Hang a weight near B to hold the rod firmly upon 

 the wire. Heat the rod by moving the gas flame back and forth 

 along the rod. Watch the position of the wire pointer. Explain 

 result. Let the rod cool. Explain the observed result. 



