PULLEYS, INCLINED PLANES, AND WEDGES 53 



2. A carpenter uses a force of 10 Ibs. in pulling a saw across a 

 piece of wood and 100 strokes of 2 ft. each to saw the wood in two. 

 What amount of work was done? 



3. A differential pulley has a large wheel 10 in. in diameter and 

 a small one 8 in. What is the mechanical advantage? 



4. A person desires 'to roll a barrel weighing 200 Ibs. into a 

 wagon that is 4 ft. above the ground. What is the most effective 

 way to do it if he can push with a force of 80 Ibs.? How long a 

 plank will be necessary? 



