Study Guide for Simple Machines
Work - Is done when a force causes an object to move in the direction of the force.
\ Simple Machine - make work easier; NOT LESS WORK
\ [[==Work = Force (N) x Distance (m)==[[
\ Example: You push a box with 8N of force and the box moves 6m. How much work is done?
\ 8N x 6N = 48J of Work
\ Power is the rate at which work is done. The faster you complete work, the more power you are generating.
\ }}Power (watts) = Work (J) / Time (s)}}
\ Example: You sand a piece of wood doing 45J of work in 5 seconds. How much power did you generate?
\ 45J / 5 s = 9 watts
\ Machine - a device that makes work easier by changing the size or direction of the force.
\ Work Input - the amount of work you put into the machine.
\ Work Output - the amount of work done by the machine.
\ {{WORK OUTPUT CAN NEVER BE GREATER THAN WORK INPUT (FRICTION CAUSES THIS).{{
\ Mechanical Advantage - the number of times the machine multiplies force.
\ Mechanical Advantage = output force (N) / input force (N)
\ [[Mechanical Efficiency - work output/work input x 100 (measured as percentage %)[[
\ \ TYPES OF MACHINES
\ 1st Class Lever - the fulcrum is between the input force and output force.
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\ \ \ \ \ 2nd Class Lever - fulcrum at one end with input force at the other end and output force in between.
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\ \ \ \ 3rd Class Lever - the input force is between the fulcrum and the output force.
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\ \ \ Pulleys - a simple machine that has a grooved wheel and a rope or cable.
\ Wheel and Axle - simple machine consisting of two circular objects of two different sizes.
\ Incline Plane - a simple machine that is a straight slanted surface (ramp).
\ Wedges - a pair of inclined planes that move. (knife/axe)
\ Screws - an inclined plane wrapped around a cylinder.
\ <<MECHANICAL ADVANTAGE FORMULAS<<
\ Lever: Distance from Input Force to Fulcrum/Distance from Output Force to Fulcrum.
\ Incline Plane: Length of ramp/ Height of ramp
\ Wheel and Axle: Radius of the wheel / Radius of the axle
\ Pulley: Count # of pulleys
\ Wedge: Length of the wedge / the thickest part of the wedge.
\ Compound Machine: two or more machines combined into one.
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