COMPOSITION OF MATTER 5 



From our study we shall become more familiar with 

 the use of this word than any definition can make us, 

 but for the sake of a definition we may say, Force is 

 the direct cause that tends to produce motion or a change 

 of motion. 



7. Forms of Energy. Like matter, energy occurs in 

 many different forms. Naturally, too, we apply names 

 to many different forces acting in the world. We shall 

 learn more about these forms of energy and these forces 

 as we study further. 



QUESTIONS 



1. What do you understand the term science to mean ? 



2. Why is scientific study divided into many branches ? Name 

 several of these branches. How are they related ? 



3. Define physics. What is included in the word matter? 

 Name some forms of matter. Can you name anything which is 

 not*matter ? 



4. What is a natural law? How are natural laws discovered? 

 Are there any that are not yet known ? Can natural laws be broken? 



5. Define energy. Define force. Carefully show the differ- 

 ence between them. 



6. Gwe examples of bodies which have energy but exert no 

 force. Give examples of forces tending to produce motion, 

 without succeeding. 



SECTION II 

 COMPOSITION OF MATTER 



8. Three States of Matter. Matter occurs in three 

 states or conditions as solids, liquids, and gases. 



Solids are those bodies that keep the same size and 

 shape unless changed "by some outside force. Glass, wood, 



