In the discussion of simple machines it is best to begin with the lever and the wheel and axle. Both of these simple machines give us a practical illustration of the principle of moments. The lever is the simpler and clearer illustration and usually presents little difficulty to a student body. The wheel and axle is a device which can be considered to be a continuously acting lever in which the radius of the wheel is the force or effort arm and the radius of the axle is the resistance arm.
©1929 by Iowa State Teachers College
"The Simple Machines,"
Science Bulletin: Vol. 2:
2, Article 7.
Available at: https://scholarworks.uni.edu/science_bulletin/vol2/iss2/7