Simple Machines
| The six simple machines are:
|
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| Although we refer to the six simple machines there
is really only three - the lever, the
wheel & axle, and the inclined plane.
The wedge, the pulley,
and the screw are modifications of the first
three. |
| THE LEVER A lever
is a device that "pivots" (or turns) against
a "fulcrum" (or point). Levers come in three
basic types - first-class lever, second-class
lever, and third-class lever.
FIRST CLASS LEVER
The fulcrum is between the load force (FL)
and the effort force (FE).
eg: a teeter totter
|
SECOND CLASS LEVER
The load force (FL) is between the
effort force (FE) and the fulcrum.
eg: a wheel barrow
|
THIRD CLASS LEVER
The effort force (FE) is between the fulcrum and the load force
(FL).
eg: tweezers, your arm
|
There are 3 variations on the 1st class lever
click here
to see what they are.
Go to
Beakman & Jax for information on levers.
You will find other sites below which
have more information on levers as well as the other simple machines.
Examples of levers.
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 |
THE WHEEL & AXLE
The wheel and axle, moves objects across distances.
The wheel, the round end, turns the axle, the cylindrical post, causing movement.
The pulley is a modification of the wheel & axle.
In the example on the left the small rod which is the
axle, is stuck rigidly to a large wheel, which
is the fan blades. When the rod turns, the wheel will also turn.
This Franklin Institute
site has lots of good information on simple machines. Don't forget to click on extra information.
Examples of the wheel
& axle.
|
| THE INCLINED PLANE
The inclined plane is the simplest of all the machines.
A common inclined plane is a ramp. A ramp works by helping you lift things more easily up
to a higher level. The longer the distance of the ramp, the easier it is to do the
work, however, it will take a longer time to do the work. The screw
and wedge are modifications of the inclined plane.
BrainPop has animated movies on the
inclined plane and the lever.
Examples of the inclined
plane. |
 |
|
THE WEDGE
The wedge is an adaptation of the inclined
plane. A wedge is really an inclined plane turned on its side,
but instead of helping you to move things to a higher level, a wedge
helps you push things apart.
This site, Lessons
on Work and Energy, has great interactive and animated lessons on work, forces and energy.
Examples of the wedge.
|
| THE PULLEY
The pulley is really a wheel and axle with a rope or chain attached. The grooved
wheel turns around an axle
(fulcrum), and a rope or a chain is used in the grove to lift heavy objects.
A pulley makes work seem easier because it
changes the direction of motion to work with gravity. Instead of lifting
up, you can pull down using your body weigh against the resistance (load,
that you are lifting). There are three types of pulleys the fixed
pulley, the moveable pulley, and the combined
pulley.
Pulley
Basics This site has a good discussion of the three main types of
pulleys. Lots of good diagrams.
Examples of the pulley.
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Combined pulley
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THE SCREW
The screw is really an inclined plane
in the round with a wedge
at the tip. Think of a typical screw. The wedge is the pointed end, the
inclined plane is the thread that wraps around the screw.
Dirtmeister's Science Reporters
is a Scholastic site which discusses
the simple machines and encourages using the scientific method.
Examples of the screw.
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As you can see by this diagram the screw is
just a
modification of the inclined plane. |
|
Edheads is a great interactive site on simple machines
Go to this Rube Goldberg site to
see how maximum effort can be used to achieve minimum results.
Want just the facts on simple machines, work, force and energy? This
Physical Sciencesite
is for you.
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