Work
the product of force and distance
Joule
the SI unit of work
Power
the rate of doing work
Watt
the SI unit of power
Horsepower
equal to about 746 watts
Machine
a device that changes a force
Input Force
the force you exert on a machine
Input Distance
the distance the input force acts through
Work Input
the work done by the input force acting through the input distance
Output Force
the force that is exerted by a machine
Output Distance
the distance the output force is exerted through
Work Output
the output force multiplied by the output distance
Mechanical Advantage
the number of times that the machine increases an input force
Actual Mechanical Advantage
equal to the ratio of the output force to the input force
Ideal Mechanical Advantage
the mechanical advantage in the absence of friction
Efficiency
the percentage of the work input that becomes work output
Lever
a rigid bar that is free to move around a fixed point
Fulcrum
the fixed point the bar rotates around
Input Arm
the distance between the input force and the fulcrum
Output Arm
the distance between the output force and the fulcrum
Wheel and Axle
a simple machine that consists of two disks or cylinders, each one with a different radius
Inclined Plane
a slanted surface along which a force moves an object to a different elevation
Wedge
a V-shaped object whose sides are two inclined planes sloped towards each other
Screw
an inclined plane wrapped around a cylinder
Pulley
a simple machine that consists of a rope that fits into a groove in a wheel
Compound Machine
a combination of two or more simple machines that operate together