Section 9.1 The Classical Simple Machines
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In this section, we are going to explore the classical simple machines. For our purposes here we will say that a simple machine is a mechanical device that changes the direction or magnitude of a force. There are six machines that are considered to be the classical simple machines: the lever, the wheel and axle, the pulley, the inclined plane, the wedge, and the screw. Each will have its own section.
Mechanical Advantage.
The mechanical advantage of a machine is how much the machine multiplies the input force. For example, if a force of 10 N into a machine results in an output force of 20 N, the mechanical advantage of 2:1. It is possible for machines to have very large mechanical advantages. For example, a car jack takes forces generate by human arms to lift a vehicle that weighs thousands of pounds.
The tradeoff of mechanical advantage is usually a tradoff between force and distance. For example, if you are using a pulley system that gives you a 10:1 mechanical advantage, it might be that you are getting 10 times the force in the output, but it’s only going to move 1/10 of the distance.
