DEFINITIONS 3 



shall apply to all bodies. We find, however, that every- 

 thing which we commonly consider to be matter occu- 

 pies space or takes up room. Therefore, 

 for want of a better definition, we may 

 say that matter is anything 

 which occupies space. 



Experiment 1. Hold a 

 tumbler bottom upward and 

 push it into water, as in Fig. 1. 

 What do you observe ? What 

 is in the tumbler before it is 

 pushed downward? Does it 

 take up room? Give a rea- p^ l 



son for your answer. Is air 



a sort of matter? Is there any form of matter that cannot 

 be seen? 



4. Natural Laws. The word law as used in science 







has a meaning with which we may not be familiar. A 

 natural law is simply a statement of a happening as it 

 occurs in nature. Such laws are not made by man. 

 From time to time men may find out new ones by 

 studying nature, and they may state them for the first 

 time; but no man can make a natural law or destroy 

 one. Doubtless there are many natural laws which 

 man has never discovered, though we can see the 

 results of their operation. 



5. Energy. This is a subject of great importance in 

 physics, and should be studied carefully. As with mat- 

 ter, it is hard to say just what energy really is ; but we 

 may say for a definition : Energy is the ability to produce 

 motion. 



