Physical Science Ch. 5

Work The transfer of energy that occurs when a force makes an object move.The transfer of energy that occurs when a force makes an object move. Motion is in direction of applied force.Motion is in direction of applied force.

Work Work = Force*distance Work is measured in Joules Joule is a Newton-meter J = N * m

Power The amount of work done in a certain amount of time.The amount of work done in a certain amount of time. The rate at which work is done.The rate at which work is done.

Power Power =work =Energy time time time time Power = Force*distance time time

Machines Make work easierMake work easier Simple machineSimple machine –Does work in only one direction Complex machineComplex machine –Does work in more than one direction –Combination of more than one simple machine

Simple Machines Incline PlaneIncline Plane WedgeWedge ScrewScrew Lever Pulley Wheel & Axle

Incline PlaneIncline Plane –Sloping surface that reduces the amount of force required to do work WedgeWedge –An incline plane with sloping sides –A moveable incline plane ScrewScrew –An incline plane wrapped in a spiral around a cylindrical post

LeverLever –Bar that is free to pivot or turn about a fixed point PulleysPulleys –Grooved wheel with a rope running along the groove. Wheel & AxleWheel & Axle –2 wheels of different sizes that rotate together

A machine where work input equals to work outputA machine where work input equals to work output –Will never exist because of friction W input = W output Ideal Machines

Mechanical AdvantageMechanical Advantage –Number of times a machine multiplies the effort force EfficiencyEfficiency –Measure of how much the work input is changed into useful work output Efficiently = W out x 100% W in W in