PROPERTIES OF MATTER 7 



All matter as we know it occupies room or space. In 

 other words, it has extension. When we pump up a bi- 

 cycle tire we find that even the air demands room for 

 itself. In the experiment with the air compressor 

 we found that the space occupied by the air could be re- 

 duced only to a limited extent. However great the pres- 

 sure might have been the air would still have occupied a 



certain amount of space. ^ 



V ^~\i 



Experiment 2. Place a coin on a s~ 



card extending slightly beyond the ^^^^^^^^^^ 

 edge of a table. Suddenly snap the Bjp| 



card horizontally. Does the coin move ? p . 



Another of our common observations is that a body 

 does not begin to move unless some force acts upon it, nor 

 when moving does it stop unless some force stops it. 

 When the card was snapped from under the coin, the coin 

 did not appear to move because the friction of the paper 

 was not sufficient to transfer any appreciable motion to it. 

 If the coin had been glued to the card, both coin and card 

 would have moved. 



Experiment 3. Revolve around the hand a small weight attached 

 to a strong rubber baud. Suddenly let go the band. Does the weight 

 keep on moving in the circular path in which it was revolving? 



When a car is moving along a level track we do not ex- 

 pect it to stop until the friction of the track or some other 

 force stops it. When we revolved the 

 weight attached to the rubber band 

 and let go the band the weight started 

 off in a straight line. It did riot con- 

 tinue in this straight line because a 

 force, gravity, pulled it down toward 

 the earth. This property which bodies 

 2. have of remaining at rest unless 



