What is Energy?
 Definition: Energy is the ability to do work.
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There are a lot of different types of energy; potential energy, kinetic
energy, thermal energy, electrical energy, light energy, sound
energy, chemical energy and nuclear energy.
Examples:
 A baseball has kinetic energy because of it’s motion.
 An outlet is a source of electrical energy
 A light bulb gives off light energy
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The energy possessed by a body by virtue of
its position relative to others, stresses within
itself, electric charge, and other factors.
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The energy which it possesses due to its
motion. It is defined as the work needed to
accelerate a body of a given mass from rest
to its stated velocity.
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Energy stored in fuel which is released when
chemicals react.

Energy stored in an object that is being
stretched , squashed, twisted, etc.
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Energy stored in an atom’s nucleus.
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Energy transferred by an electric current.
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Energy transferred through waves and light
particles.
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Energy transferred through sound waves
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Energy of an object due to its temperature.
This is partly because of the random kinetic
energy of the particles of the object.
The meaning of words can be changed depending on where you use
them. For example, “work” is the place someone may go to make
money. Similarly, you do house “work” or home “work” when you help
around the house or study school subjects at home. These are the
everyday meanings of “work”.
In physics, work is used in a difference sense.
Work is done only when an object is moved by applying a force
to it.
 when you throw a baseball, you do work on the ball
 When you pull a toboggan, you do work on the sled
Work is done when a force moves an object.
For example, it takes work to lift a heavy
barbell, but it does not take work to hold the
barbell over your head.
In either case, you would say you were working
hard. But, for work to be done, the object must
move.
It takes about 100N of force to push a lawn mover
forward.
How much work would it take if you walked 1000m?
Steps in Solving in the Problem:
Step 1: Write out the formula.
W=Fxd
Step 2: Substitute the numbers. W=100N x 1000m
Step 3: Do the calculation.
W = 100 000 Nm
or 100 000 J
Step 4: Summarize the answer.
100 000 joules of work would be done.
Step 4
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Definition: A machine that has only one movement

The oldest simple machine is a ramp (inclined plane)
Complete/Hand-In
 CYU pg. 133 #1-4
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Levers: bars that pivot on a fulcrum
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Lever Parts
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◦
◦
◦
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Fulcrum: the supporting point
Load: the object being moved by the lever
Effort: the force required to move an object
Load distance: distance from the fulcrum to the load
Effort distance: distance from the fulcrum to the effort
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In first class levers, the fulcrum is between
the load and the effort.
First class levers are used for lifting, prying,
and cutting.
◦ Example: a pair of scissors, the fulcrum is the screw
that holds the scissor blades together
◦ Example: a pair of plyers
In second class levers, the
fulcrum is at one end and the
effort at the other end with the
load in the middle.

◦ Example: wheelbarrows and nutcrackers
In third class levers, the
fulcrum is at one end and
the effort is between the
load and the fulcrum.

◦ Examples include: axes, rackets, and hockey sticks.
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Your body has levers too!
First class: the triceps are the
muscles that reach from the
back of your upper arm and
around your elbow.
Third class: the biceps the
large muscle at the front of
your upper arm, provides
effort.
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
A distance multiplier moves a load through a
large distance but requires a short effort
distance.
A fishing rod is an example of a distance
multiplier. In this machine a small movement
by the effort (when you make a cast)
produces a much larger movement of the
load (fishing line moves meters away).
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A force multiplier is a simple machine that
easily moves a large load.
A small force on the effort end of the lever
puts a large force on the load.
Complete/Hand-in
CYU Page 139 #1-6
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A pulley is a simple machine consisting of a
grooved wheel on which a rope or cable
turns.
Fixed Pulley
 A pulley that does not move and does not
change the effort required.
Movable Pulleys
 A pulley that moves with the load and
reduces the effort required.
Wheels and Axels
 A simple machine that consists of a wheel
turning a smaller rod
 Every time you turn a doorknob, you operate
a wheel and axel machine.
Complete/Hand-in
CYU page 144 #1-5
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When your car is stuck in a snow drift, usually
it does not help to spin your tires.
It wastes energy (not efficient), and often gets
you stuck even worse.
When a machine is used, the machine will
lose energy through:
◦ Friction between moving parts
◦ Heat given off by the cooling system or exhaust
◦ Poor combustion of fuel
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A machine’s efficiency is a comparison of the
work the machine does with the energy it
uses to do that work.
No machine is 100% efficient. Meaning, the
work output does not equal the work input.
Most of the energy used in Canada comes
from burning fossil fuels, which lead to
environmental concerns:
◦ Burning fossil fuels contributes to global climate
change and air pollution
◦ Fossil fuels are non-renewable

One way to deal with concerns related to
burning fossil fuels is to reduce the amount
of energy you use, either by using machines
less or by changing to more efficient
machinery.
◦ Use energy efficient appliances
 Use energy from renewable
sources.
oWindmills and solar panels provide
energy from renewable sources
Complete/Hand-in
CYU page 149 #1-4
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Complete/Hand-in Assignment #7
Complete/Hand-in Simple Machines Research
Project
Study for Unit B Test