A device that decreases the amount of input force needed for a task by changing how force is applied.
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Mechanical advantage
The ratio between effort force and resistance force, indicating how much a machine multiplies the force applied to it.
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Kinetic energy
The energy of motion that an object possesses based on its mass and velocity.
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Potential energy
Stored energy that an object has due to its position or state, such as gravitational potential energy from height.
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Work
The transfer of energy that occurs when a force is applied to move an object in the direction of the force.
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Power
The rate at which work is done or energy is transferred over time.
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Friction
A force that opposes motion and causes energy loss in real machines and moving objects.
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Energy conservation
The principle that energy cannot be created or destroyed, only transferred or transformed from one form to another.
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Gravitational potential energy
The potential energy an object has based on its mass and height above a reference point, calculated as mass times gravitational acceleration times height.
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Reference point
A fixed position or location used as a basis for measuring quantities like kinetic energy and potential energy.
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Velocity effect on kinetic energy
Doubling velocity has a greater effect on kinetic energy than doubling mass because kinetic energy depends on velocity squared.
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Work versus power
Work is the total energy transferred, while power is the rate at which work is performed; two people doing the same work in different times have the same work but different power.
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Machine energy creation
A machine cannot create energy; it can only transfer or transform energy from one form to another.
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Input and output work
In a real machine, input work must be greater than output work because some energy is lost to friction.