Simple machines are the simplest objects that can be used to magnify and/or change the direction of a a force when doing work.
Examples of the Six Simple Machines:
You should know about forces, torque, and work to fully appreciate this lesson.
Simple machines are used to change the magnitude and direction of applied forces.
We represent the change in magnitude of a force by the mechanical advantage.
The mechanical advantage is the ratio of the load force that is moved to the effort force
that is applied.
We talk about two kinds of mechanical advantage: real mechanical advantage and ideal mechanical advantage.
Real mechanical advantage is simply RMA = FL/FE, and is based on real measurements of a real simple machine.
Ideal mechanical advantage uses the symbol IMA, and is calculated based on the ideal model of the machine. It is always a function of the dimensions of the machine.
Ideal machines are massless, frictionless, and inelastic (in other words, they do not bend, stretch, twist, squish, or otherwise deform.
The IMA can be calculated using one of three methods:
Efficiency is the ratio of the useful work you get out of a machine to the work you put into it:
Efficieny = Wout / Win * 100.