JOAN CARTAN-HANSEN, HOST: A simple machine is a tool that helps us do work.

They don't have engines or use electricity.

They use clever shapes to help us move, lift, cut, and other types of work.

Let's find out more about simple machines.

[MUSIC] CARTAN-HANSEN: Here's a question for you... What do the great pyramids of Egypt have in common with the lid on a jar of peanut butter?

Student: I don't know, what?

CARTAN-HANSEN: Both are examples of what a simple machine can accomplish.

Student: A simple machine?

What's that?

CARTAN-HANSEN: Simple machines help us make better use of our muscles to use forces to do work.

Don't be fooled by their name.

Simple machines help create things that are very complex.

A simple machine controls the direction of the force we apply.

And they're very handy because they make many movements and jobs easier to accomplish.

The six simple machines are: Kid 2: Inclined plane Kid 3: screw Kid 4: wedge Kid 5: pulley Kid 6: wheel and axle Kid 7: lever CARTAN-HANSEN: The simplest of the simple machines is the inclined plane.

See that wheelchair ramp?

That ramp is an example of an inclined plane.

It allows someone to go inside without trudging up the stairs.

Even though you're going a longer distance, it takes less effort to go inside using an inclined plane.

Next are pulleys.

There are pulleys in most elevators, and your fishing pole has a pulley too.

A pulley helps you move something up or down.

It's a special wheel with a rope around it.

When you give the rope a tug the object at the other end can be easily lifted.

If you combine several pulleys, you can lift something that normally you'd never be able to carry.

Then there is the lever.

The lever is probably the oldest simple machine.

One example of a lever is a seesaw.

Every lever has a fulcrum.

The fulcrum is the point on which the lever rests and on which it can move.

The way a lever works is: downward motion on one end results in upward motion at the other.

You can raise something heavy using a lever.

Scissors are also a good example of a lever.

The next simple machine is the wheel and axle.

It's best described with a good look at the tires of a car.

A wheel and axel are connected in a way that allows them to rotate together.

The wheel is locked to a central axle.

When one turns, they both turn.

The wheel and axle allow you to move the heavy car.

A doorknob has a wheel inside it that goes around a central rod, the axle.

When you turn the doorknob, you're using a wheel and axle to open a door.

Next is the wedge.

It's shaped a little like an inclined plane.

The shape allows force to be applied to the broad end and be redirected and concentrated on the sharp edge.

People often use a wedge to split wood.

Your teeth are also like a wedge when you take a bite of food.

Doorstops, and shovels are examples of things the use wedges.

And finally, there's the screw.

A screw is a type of fastener to hold things together.

A screw has a spiral ridge called a thread.

These kinds of screw are used to build things.

But there are other uses for screws.

Every time, you take off a jar lid, you're seeing a screw in action.

You're using a screw when you screw in a light bulb.

Simple machines reduce the effort needed to accomplish a job.

They help do work with less effort by changing the force and distance needed to get something done or by changing its direction.

Humans have used simple machines for thousands of years.

Humans used simple machines to build the Great Pyramids, and today, we use them every day!

Simple machines have lasted because they help us do work more work easily.

If you want to learn more about simple machines, check out the Science Trek website.

You'll find it at ScienceTrek.org.

(Music) ANNOUNCER: Presentation of Science Trek on Idaho Public Television is made possible through the generous support of the Laura Moore Cunningham Foundation, committed to fulfilling the Moore and Bettis family legacy of building the great state of Idaho, by the Idaho National Laboratory, mentoring talent and finding solutions for energy and security challenges, by the Friends of Idaho Public Television, and by the Corporation for Public Broadcasting.