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Chap. 5 EM
Term | Definition |
---|---|
work | the transfer of energy that occurs when a force makes an object move; measured in joules |
power | the amount of work done, or the amount of energy transferred, divided by the time required to do the work or transfer the energy; measured in watts (W) |
machine | device that makes doing work easier by increasing the force applied to an object, changing the direction of an applied force, or increasing the distance over which a force can be applied. |
input force | the force applied to the machine |
output force | the force applied by the machine |
mechanical advantage | ratio of the output force exerted by a machine to the input force applied to the machine. |
efficiency | ratio of the output work de by the machine to the input work done on the machine, expressed as a percentage. |
simple machine | machine that does work with only one movement--lever, pulley, wheel and axle, inclined plane, screw, and wedge. |
lever | simple machine consisting of a bar free to pivot about a fixed point called the fulcrum. |
pulley | simple machine that consists of a grooved wheel with a rope, chain, or cable running along the groove; can be either fixed or movable |
wheel and axle | simple machine that consists of a shaft or axle attached to the center of a larger wheel, so that the shaft and the wheel rotate together. |
inclined plane | simple machine that consists of a sloping surface, such as a ramp, that reduces the amount of force needed to lift something by increasing the distance over which the force is applied. |
screw | simple machine that consists of an inclined plane wrapped in a spiral around a cylindrical post. |
wedge | simple machine that is an inclined plane with one or two sloping sides |
compound machine | machine that is a combination of two or more simple machines |