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 H 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. 



b. 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 Ji 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. 



