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WorkPower
Simple MachinesEnergy
WorkWork is done on an object when the object moves in the same direction in which the force is exerted.
Formula: Work = Force x Distance
Units:Work is measured in Joules (J)Force is measured in Newtons (N)Distance is measured in meters (m)
PowerPower is the rate of transfer of energy or the
rate at which work gets done.
Power = Work / Time
Power = Watts (W)
Work = Joule (J)
Time = seconds (s)
PulleyA pulley is a simple machine made of a grooved
wheel with a rope or cable wrapped around it.
Types of PulleysSingle Fixed Pulley:
attached to the structure, like a flag pole
Does not change the amount of force applied
Does change direction of the force
Types of PulleysSingle Movable Pulley:
this pulley is attached to an object you wish to move
Decreases the amount
of input force neededDoes not change the
direction of the force.
Types of PulleysBlock and Tackle:
combination of fixed and moveable pulleys
Decreases input force even more than a moveable pulley
Mechanical AdvantageMA = Output force / Input force
MA also equals the number of sections of ropethat support the pulley
Inclined PlaneAn inclined plane is a flat, sloped surface.
An inclined plane allows you to exert your input force over a longer distance
Ideal Mechanical Advantage
MA = Length of the incline divided by the height of the incline .
LeversA lever is a rigid bar that is free to pivot, or
rotate, at a fixed pointThe fixed points that a lever pivots on is called a
fulcrum
Ideal Mechanical Advantage
MA = Distance from fulcrum to input force ÷ Distance from fulcrum to output force
Input Force
Output Force
Types of LeversLevers are classified according to the location of
the fulcrum relative to the input and output forces
1st Class 2nd Class 3rd Class
Examples of Levers Third Class
Three Other Simple Machines
Wheel and Axle – a machine consisting of a wheel that turns an axle so that the two parts rotate together.
Wedge – a machine with at least one slanting side ending in a sharp edge.
Screw – a machine that contains an inclined plane wrapped around a post.
Compound MachinesA machine that is made of two or more simple
machines.
EnergyEnergy is the ability to do work or cause change.
Kinetic energy is the energy an object has due to its motion. Formula: KE = ½ mv2
Ex: a ball dropped off of a ledge, a bike going up a hill and down a hill
Potential energy is stored energy that results from the position or shape of an object.Ex: holding a ball at the top of a ledge, a bike at the top of the hill
Gravitational Potential Energy
(GPE) is the energy related to an objects height. The higher an object is raised the more GPE.
Formula: GPE = Weight (N) x Height (m)
Elastic Potential EnergyElastic potential energy is the energy associated
with objects that can be stretched or compressed.
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