14 terms

work

the transfer of energy to an object by using a force that causes the object to move in the direction of the force (calculated by multiplying force by distance)

joule

the unit used to express energy (symbol, J); equivalent to the amount of work done by a force of 1 N (Newton) acting through a distance of 1 m (meter) in the direction of the force

machine

a device that helps do work by either overcoming a force or changing the direction of the applied force

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 extended

mechanical advantage

a number that tells how many times a machine multiplies force (calculated by dividing output force by input force)

mechanical efficiency

a quantity, usually expresses as a percentage, that measures the ratio of work output to work input (calculated by dividing work output by work input and multiplying the result by 100)

lever

a simple machine that consists of a bar that pivots at a fixed point called a fulcrum; used to apply a force to a load

pulley

a simple machine that consists of a grooved wheel over which a rope, chain, or wire passes

wheel and axle

a simple machine consisting of two circular objects of different sizes; the wheel is the larger of the two circular objects (its mechanical advantage is calculated by dividing the radius of the wheel by the radius of the axle)

inclined plane

a simple machine that is a straight, slanted surface, which facilitates the raising of loads; a ramp (its mechanical advantage is calculated by dividing its length by its height)

wedge

a simple machine that is made up of two inclined planes and that moves; often used for cutting (its mechanical advantage is calculated by dividing its length by its greatest thickness)

screw

a simple machine that consists of an inclined plane wrapped in a spiral around a cylinder (its mechanical advantage is calculated by dividing the length of its inclined plane by its height)

compound machine

a machine made of more than one simple machine