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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