IV. MATTER AND FORCE 



SOME PROPERTIES OF MATTER, AND CHANGES IN 

 MATTER DUE TO FORCE 



1. Into a test tube already filled with water, attempt to 

 put considerably more water without causing any over- 

 flow. What constitutes a satisfactory "explanation" of 

 the inability to do this? 



Our knowledge of the existence of the water, and of the 

 existence of any other portion of matter, involves the fact 

 that they " occupy space, " and that no two bodies can occupy 

 the same space at the same time. To say that matter is 

 that which occupies space tells what matter is by naming a 

 distinguishing characteristic. This does not in any way 

 imply that scientists themselves have any complete knowl- 

 edge of the real nature of matter, nor does it mean that there 

 may not exist that which takes up no room, and is there- 

 fore not matter. Indeed, the study of Physics is quite as 

 much concerned with that which as force (the cause of changes 

 in matter) has itself no material existence. 



2. Every portion of matter extends outward from a point 

 within the body in three different directions, giving to the 

 body its dimensions of length, breadth, and thickness. Ex- 

 tension, impenetrability, form, size, and density are closely 

 related properties of matter. Give the definitions for 

 each. 



3. Push a book lying upon the table, and note that it 

 can be moved that it has mobility. Now let it alone, 



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