What do you think of when you hear the word "machine"?
A machine is something that makes it easier to do things.
Did you know that there are some machines out there
that are very simple?
They often have no or very few moving parts
and no motor!
Really.
There are six basic types of simple machines.
They are: the lever, the inclined plane,
the wheel and axle, the pulley,
the screw and the wedge.
These simple machines make work easier
by letting us move things with less force.
Levers let us use less force
by having the force act over a greater distance.
For example, on a seesaw,
a smaller person can lift a larger person
if the smaller person
moves further away from the pivot point.
An inclined plane will spread the force
over a greater distance too.
Instead of lifting a heavy rock straight up,
you can use a ramp to reduce the force needed to lift the rock
but you need to drag the rock for a longer distance.
Sometimes inclined planes
do not look like inclined planes.
Take, for instance, stairs.
Stairs make it easier for us to go up
because the force is spread over a greater distance.
Ramps make it even easier for us to go up.
Ramps also help people who cannot use stairs
like people in wheelchairs.
Speaking of wheels...
the wheel and axle make work easier
because they reduce friction when you move something.
Initially, humans used log rollers or rocks to move things,
and they had to take rollers from behind
and put them in front.
With the axle, the wheel could be attached on the end
and turn freely about the axle.
The axle would support the load.
Did you know if you have a rounded surface,
you could have square wheels?
This might have been how Egyptians
moved the large blocks of stone for the pyramids.
Pulleys are made up of a rope wrapped around a wheel.
Pulleys make moving things easier
by changing the direction of the force.
Which is easier to do?
Pulling up on a rope or pulling down on a rope?
With a pulley, you can pull down on a rope.
You can add a weight onto the rope,
or have more people pull down,
making it easier to lift your load.
Using multiple pulleys
lowers the force needed to lift something by using longer ropes.
Screws are actually inclined planes.
See this triangle?
It looks like a ramp, right?
If I twist the triangle around this pipe,
you will see a spiral.
It looks like a screw.
Screws change turning force into straight line force.
We have two general types of screws:
attaching screws and lifting screws.
Attaching screws will hold things together.
Lifting screws will move things.
You have probably seen a lifting screw during the wintertime.
Our last simple machine is the wedge.
Wedges can cut or separate things.
A wedge is also related to the inclined plane
because it is really two inclined planes stuck together.
Inclined planes don't move
but help us move things over the ground.
Wedges lift things as they move.
They are like moving inclined planes.
A wedge can cut and separate hard things like wood
or soft things like water and snow.
Many mechanisms and complicated machines
are combinations of simple machines.
If you look around, you will start to notice
all of the simple machines that are out there
making our lives easier.
And, we can also use simple machines for fun!