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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 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 | a force that is applied to a machine |
output force | a force that is applied by a machine |
mechanical advantage | ratio of the output force exerted by 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, |
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 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 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. |