Simple Machines Machine- A device that makes work easier by changing the speed , direction, or amount of a force. Simple Machine- A device that performs work with only one movement. Simple machines include lever, wheel and axle, inclined plane, screw, and wedge. Ideal Mechanical Advantage (IMA)- A machine in which work in equals work out; such a machine would be frictionless and a 100% efficient IMA= De/Dr Actual Mechanical Advantage (AMA)- It is pretty much the opposite of IMA meaning it is not 100% efficient and it has friction. AMA= Fr/Fe Efficiency- The amount of work put into a machine compared to how much useful work is put out by the machine; always between 0% and 100%.