Question | Answer |
work | the transfer of energy to an object by using a force that causes the object to move in the direction of the force |
joule | the unit used to express energy; equivalent to the amount of work done by a force of 1 N acting through a distance of 1 m in the direction of the force (symbol, J) |
power | the rate at which work is done or energy is transformed |
watt | the unit used to express power; equivalent to a joule per second (symbol, W) |
power | 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 exerted |
mechanical advantage | a number that tells how many times a machine multiplies force |
mechanical efficiency | a quantity, usually expressed as a percentage, that measures the ratio of work output to work input in a machine |
lever | a simple machine that consists of a bar that pivots at a fixed point called a fulcrum |
pulley | a simple machine that consists of a 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 |
inclined plane | a simple machine that is a straight, slanted surface, which facilitates the raising of loads; a ramp |
wedge | a simple machine that is made up of two inclined planes and that moves; often used for cutting |
screw | a simple machine that consists of an inclined plane wrapped around a cylinder |
compound machine | a machine made of more than one simple machine |