THE APPLICATION TO SOME OTHER MACHINES 339 



remember that we can get no more work out of a machine 

 than we put into it. The law of machines may be stated 

 as follows : The force applied to a machine times the distance 

 through which it acts equals the resistance overcome times 

 the distance through which it is overcome. That is, if you 

 move a 2oo-pound weight i foot by applying a force of 20 

 pounds, this force would have to act through a space of 

 10 feet. 200X1 = 20X10. 



Unit of work. The term we use for the unit of work 

 is the foot pound. This is exactly what its name indicates. 

 If we lift a pound one foot, the result is a foot "pound, or 

 if we lift four pounds four feet from the ground, we do 

 sixteen foot pounds of work. In other words, the work 

 equals the weight multiplied by the distance. 



The application to some other machines. If we now 

 apply this rule to such other machines as the meat chop- 

 per, clothes wringer, coffee 

 grinder, and ice cream 

 freezer; we find that we can 

 easily estimate the amount 

 of force which must be ex- 

 erted to make them do their 

 work. In the machines just 

 mentioned, we apply force 

 by the hand with a crank or 

 handle which is revolved 

 through a circular path. All 

 of the machines belonging 

 to this type are known as 

 the crank and axle, or the wheel and axle type. The work 

 is done at a point on the circumference of the axle. If 

 the circumference of the roller of the clothes wringer is 



The clothes wringer; a crank and axle 

 machine. 



