Energy (The ability to do work)

Potential energy: due to position ex. bungee jumper

Kinetic energy: due to motion ex. baseballThermal energy: heat ex. stove elementElectrical energy: ex. power outletLight energy: ex. light bulbSound energy: ex. speakerChemical energy: found in chemicalsNuclear energy: found in uranium

WorkForce: push or pull, measured in Newtons (N)Distance is measured in meters (m)Work = force x distanceWork is done when a force is applied to an

object and it movesIf you are pushing on a wall is this work?If you lift a box and walk across a room, is

this work?

Incline PlaneA simple machineAllows less effort to be expended during a

task because instead of going straight up or down a steep hill

You go back and forth across a steep hillYou can push an object up or down instead of

lifting it

LeversThey are bars that pivot on a fulcrumAn effort force is required to move a loadThe distance from the load to the fulcrum is

the load distanceThe distance from the fulcrum to the effort is

the effort distance

First Class LeverThe fulcrum is between the load and the

effortUsed for lifting, prying, cuttingEx. teeter totter, scissors, pliers, claw

hammer when pulling nails, crowbar, oar on a rowboat or raft

Draw the picture on page 134

Second Class LeversThe fulcrum is at one end, the effort at the

other end and the load in between themEx. wheelbarrow, bottle opener, nut cracker,

Achilles tendonDraw the picture on page 136

Third Class LeverThe fulcrum is at one end, the load at the

other end and the effort in between themUsed when a job requires speedEx. axes, rackets, tongs, brooms, tweezers,

shovel, ice cream scoop, hammer when hammering, hockey stick, fishing poll, bat

Draw the picture on page 137

Levers in the BodyTriceps: class 1Biceps: class 3See page 138

Distance MultipliersExamples include fishing rods, hockey sticks,

axes, malletsThey move a load through a large distance

with little effort distanceWhen distance is multiplied there is a speed

advantageCommonly in third class levers

Force MultiplierA simple machine which moves a large load

easilyA small effort on the lever, puts a large force

on the loadFirst and second class levers are force

multipliers

PulleysA grooved wheel with a rope threaded around

itThe load is attached at one end of the rope,

effort is applied at the other endWhen the effort can support the load, the

system is in equilibrium

Fixed pulley: the effort force is equal to the load force

Moveable pulley: moves with a load

Wheel and AxleEvery time you turn a doorknob you rotate a

wheel and axle, the doorknob is a wheel that turns the axle

A screwdriver is a wheel and axle, the handle acts as the wheel, the screw is the axle, as you rotate the handle the screw moves

Machines Loose Energy ByFrictionHeatPoor combustion (if fuel is used)

EfficiencyA comparison to the work done with the

energy used that is used to do workNo machine is 100 % efficientWhen you cook food, some heat is lost to

warm the air above the pot (convection)

In the HouseBeing efficient is a way to conserve money as

well as protect the environmentAppliances around the home have energy

ratings, measured in kilowatt hoursA kilowatt hour is the amount of electricity

used when 1000 watts is used for 1 hour

Fossil FuelsMost of the energy in Canada comes from

the burning of fossil fuels (oil, gas)They pollute the environment and are

non-renewableTo solve these problems we could reduce

the amount of energy we use, such as walk instead of drive

Replace inefficient appliances with more efficient ones, such as a new fridge

Use renewable energy sources

Renewable EnergyWind powerSolar powerBallard fuel cell