1. Machines 3. What are Machines?

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

3. 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

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

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

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

7. Some machines do more than one of these things

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

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

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

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

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

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

14. If there were no machines
you would have to walk everywhere

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

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