Science-Work and Machines

work

force x distance

Joule

SI unit of work and energy

Power

the rate at which work is done

Watt

SI unit of power

horsepower

a common unit of power, equal to about 746 watts

machine

A device that makes work easier

input force

the force you exert on a machine

output force

the force applied by the machine

input distance

the distance the input force acts through

output distance

the distance an output force acts through in a machine

work input

the work done on a machine; the product of the input force and the distance through which the force is exerted

work output

the work done by a machine; the product of the output force and the distance through which the force is exerted

Actual Mechanical Advantage (AMA)

the ratio of the output force to the input force in a machine

ideal mechanical advantage

the mechanical advantage of a machine in the absence of friction

Efficiency

The percentage of the input work that is converted to output work

lever

A rigid bar that is free to move around a fixed point

wedge

A device that is thick at one end and tapers to a thin edge at the other end.

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

wheel and axle

Two different sized circular objects that are attached together and turn as one.

inclined plane

a flat, sloped surface

Friction

A force that opposes motion between two surfaces that are in contact