Welcome to a world full of
machines!
 There are machines all around us!
 Can you identify a few machines in the Lab?
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Machines – tools that helps us do
work
 Machines help us by:
• Changing the amount of force required to move
an object.
• Changing the direction of the force.
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What is Force?
 A force is a push or pull that changes the
shape or motion of an object.
• Example: When you kick a soccer ball, you are
applying a force and it changes direction.
 The unit used to measure force is the
Newton (N).
3
What is Work?
 Work is the result of a force moving an
object over a distance.
• Example: When you pick up a textbook and put
it on the desk, you are doing work.
work = force applied x distance
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What is Energy?
 Energy is the ability to do work.
 Example: I must have energy to run the mile.
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Why do we need simple
machines?
 Work means that we are exerting force and
moving something.
 The 6 simple machines make our work easier.
 In most cases, we apply a lesser force over a
greater distance.
 The work is made easier (requires less force),
but the amount of work done remains the
same.
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Simple Machines
 Have few or no moving parts.
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The 6 Simple Machines
 All machines are made up of some of the 6
simple machines. They are:
•
•
•
•
•
•
Wheel and axle
Pulley
Lever
Wedge
Screw
Inclined Plane
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The Inclined Plane
 It is a slanted
surface or ramp.
 It makes moving
objects easier.
 Roads are also
inclined planes.
Instead of going
straight up, roads go
up at small angles.
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The Wedge



A wedge is usually a triangle
shape with a sharp point and is
two inclines planes back-toback.
A wedge is used to split,
tighten, cut or secure a hold.
If you apply force at one end,
the wedge will go between
something, in this case an ax
splits a piece of wood.
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Different Functions of Wedges
Wedges that split:
 Your teeth
 Every time you bite
into something, you
are using a wedge.
 Wedges that cut:
 A saw
 A knife

Wedges that tighten:
 A doorstop to keep the
door open.
 Wedges that secure:
 A nail holds wood to a
wall or other wood.

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The Screw




A screw is essentially an inclined plane
(the threads) wrapped around a shaft.
It is used to fasten two things together.
When you turn it, the threads cut a
groove in the material, making a hole.
The groove holds the screw tightly in
place.
To remove the screw you turn it the
opposite way, you can’t just pull it out.
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Lever
 Made of a board or bar set on top of a
fulcrum
 Used to lift weight
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Levers

There are four parts to
a lever:
•
•
•
•
Lever (board or rod)
Load
Force
Fulcrum (support or
balance)
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First Class Lever
In a first class lever,
the fulcrum is
between the effort and
the load.
 The effort required to
lift the load is
decreased the closer
the fulcrum is to the
load.
 Example: seesaw

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Second Class Lever
In a second class
lever, the fulcrum is at
the end, with the load
in the middle.
 Example: wheelbarrow

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Third Class Lever
In a third class lever,
the fulcrum is at the
end with the effort in
the middle.
 This class of lever is
used to gain distance
as the effort is greater
than the load.
 Example: tweezers,
arm

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The Wheel and Axle
A wheel turns on a post to
help move things easily and
quickly
 Two or more wheels are
connected by an axle.
 The wheel turns with or
around the axle.
 This car wheel has a big
axle that it rotates around
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when the car moves.

Why do we need wheels?
 Wheels help us move heavy objects.
 They roll easily.
 Did you know a doorknob is really two
wheels connected by an axle? You can’t
see the axle because it’s inside the wheels,
but it’s there!
 If there wasn’t an axle, the doorknob
wouldn’t turn!
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Gears
A gear is a wheel with teeth.
 The teeth fit in between each
other and turn.
 When one gear turns, its teeth
push against the teeth of the
other gear and they both turn.
 There are gears on your bike, on
a can opener and on an egg
beater.

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Pulleys




A pulley is a wheel with a rope
running over it. The wheel has a
groove, called a sheave, and it keeps
the rope from slipping off the wheel.
Remember, since there is a wheel in
a pulley there also has to be an axle!
A single pulley makes work easier
by reversing the direction of the
effort (working with gravity, instead
of against it).
These two men are using a pulley to
help them lift their heavy bucket.
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The 6 Simple Machines
Lever
Wheel and
Axle
Inclined Plane
Screw
Pulley
Wedge
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Compound Machine
 Two or more simple machines working
together
 Examples
• bike
• car
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