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Chapter 5
Term | Definition |
---|---|
work | transfer of energy that occurs when a force makes an object move; measured in joules. |
power | 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 the watts. |
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 that is 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 done 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 & axle, inclined plane, screw, & wedges. |
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 alonf the groove; can be either fixed or movable. |
wheel & axle | simple machine that consists of a shaft or axle attached to the center of larger wheel, so that the shaft & the wheel rotates together. |
inclined plane | simple machine that consists of a sloping surface, such as a ramp, that reduces that amount of force needed to life 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 | substance formed from two or more elements in which the exact combination & proportion of elements is always the same. |