62 



LABORATORY EXERCISES 



a spool is fastened to the board. The axle of the spool may be 

 a wire nail that is nearly as large as the hole in the spool. It 

 may be fastened to the edge of the board by means of two- 

 pointed tacks. 



For the weight (Fig. 27) use a book in a sling, and a cord or 

 tape long enough to go over the edge. Under the book place 



FIG. 26. 



FIG. 27. 



two round dowels about 8 cm. (3 in.) long, or use spools. 

 Best of all, use a small cart with spools for wheels. 



Make the plane half as high as it is long, and see if one book 

 will support two. Then make it J as high as it is long, and see 

 if one book can support three. If you use a cart, you must 

 make allowance for the weight of the cart. 



6. Simpler Form. Use a drawing board, moulding board, 

 or ironing board for the inclined plane. Up the plane roll an 

 unopened tin fruit can, such as a can of tomatoes or peaches. 

 If the plane is vertical, how much force must you exert? If it 

 is half as high as long? If it is H as high as long? If it is 

 horizontal? 



Find out where you can see an inclined plane in actual use, 

 watch the operation, and describe it. 



