THE INCLINED PLANE -AND WEDGE 171 



b. Make the inclined plane steeper or less steep and 

 find the pull necessary to pull the car up it. Measure the. 

 length of the plane and the height -of the high end of the 

 plane. Multiply the pull up the plane by- the length of 

 the plane and compare it with -the result obtained by 

 multiplying weight of the car, with its load, by the height 

 of the end of the plane. Should you draw your conclu- 

 sions from this? Finally draw your conclusions. Can 

 you see any relation between the lever and the inclined 

 plane? 



A very common use of the inclined plane is made in 

 splitting stumps. The inclined 

 plane in this case is called a 

 wedge. Instead of anything 

 moving up the inclined plane the 

 inclined plane, the wedge, moves 

 and the material has to Separate 

 as the wedge is driven into it. 

 The advantage is just the same 

 as in the last experiment. Many 

 other machines are very much 

 like the lever and the wedge, although they are giveri 

 other names. We shall learn more about machines next 

 year, but it is most important to know just how these two 

 aid us, 



Review Questions, 27, 



1. Why is the image of an object in a mirror right 

 Side up, but in a pinhole camera upside down? 



