Machines 3. What are Machines?

It is easier to pull a large rock in a wagon than to push it on the ground

It is easier to tighten a nut with a wrench than with your fingers It is easier to raise a car with a jack than to lift it yourself

A wagon, a wrench, and a jack are all machines Machines make work easier

Some machines cut down on friction Others can change the amount of force used

Still others can change the direction of a force Gears can do this

Some machines do more than one of these things

It is easier to pull a bunch of dogs in a wagon because the wagon’s wheels cut down on friction

When a rock is on the ground all of the rock that is touching the ground provides friction

When the rock is in the wagon only the wheels touch the ground

The wheels use the friction with the ground to turn and move the rock

It is easier to tighten a nut with a wrench because the wrench makes the amount of force larger

Another machine that changes the direction of force is a pulley When you pull down on a drapery cord the drapes open

If there were no machines you would have to walk everywhere

There would be no bicycles, cars, trains, buses, or planes There would be no wagons or wheelbarrows to move things

It is hard to imagine what life would be like without machines