1. Welcome to a world full of machines!
There are machines all around us!
What kinds of machines are in your house?

2. Machines – tools that helps us do work
Machines help us by:
Changing the amount of force required to move an object.
Ex. Pulling bricks in a wagon is easier than carrying them in your arms!
Changing the direction of the force.
Ex. Pushing down on one end of a see saw to make the other end move up!

3. Force and Work
A force is a push or pull that changes the shape or motion of an object.
Example: When you kick a soccer ball, you are applying a force and it changes direction.
Work is the result of a force moving an object over a distance.
Example: When you pick up a textbook and put it on the desk, you are doing work.

4. Why do we need simple machines?
Work means that we are exerting force and moving something.
The 6 simple machines make our work easier.
In most cases, we apply a lesser force over a greater distance.

5. Why do we need simple machines?
Using a simple machine makes the work easier because we apply less force to accomplish the same task.
The amount of work done remains the same with or without a simple machine.

6. Why do we need simple machines?
Less distance to travel, but more effort needed.
Greater distance to travel, but less effort needed.
Total amount of work is the same because the height of the ramps is the same!

7. The 6 Simple Machines
All machines are made up of one or more of the 6 simple machines. They are:
Wheel and axle
Screw
Pulley
Lever
Wedge
Inclined plane

8. The Inclined Plane It is a slanted surface or ramp.
It makes moving objects easier.
Roads are also inclined planes. Instead of going straight up, roads go up at small angles.

9. The Screw
A screw is essentially an inclined plane (the threads) wrapped around a shaft.
It is used to fasten two things together.
When you turn it, the threads cut a groove in the material, making a hole. The groove holds the screw tightly in place.

10. The Wedge
A wedge is usually a triangle shape with a sharp point and is two inclines planes back-to-back.
A wedge is used to split, tighten, cut or secure a hold.
If you apply force at one end, the wedge will go between something, in this case an ax splits a piece of wood.

11. Different Functions of Wedges
Wedges that split:
Your teeth
Every time you bite into something, you are using a wedge.
Wedges that cut:
A saw
A knife
Wedges that tighten:
A doorstop to keep the door open.
Wedges that secure:
A nail holds wood to a wall or other wood.

12. Levers There are four parts to a lever: Lever (board or rod) Load
Force or effort
Fulcrum (support or balance)
Force
Load
Lever
Fulcrum

13. First Class Levers The fulcrum is in the middle.
The force applied moves the load in the opposite direction.
There is a mechanical advantage because you need less force to move the heavier load.
Ex. Scissors, see-saw

14. Second Class Levers The Load is in the middle.
The force applied moves the load in the same direction.
There is a mechanical advantage because you need less force to move the heavier load.
Ex. Nutcracker, wheelbarrow

15. Third Class Levers The effort is in the middle.
The force applied moves the load in the same direction.
There is no mechanical advantage because you need more force to move the load.
It makes the load move further (Ex. Fan moving air).
It speeds up the load (Ex. Puck coming off a hockey stick).

16. The Wheel and Axle Two or more wheels are connected by an axle.
The wheel turns with or around the axle.
This car wheel has a big axle that it rotates around when the car moves.

17. Why do we need wheels? Wheels help us move heavy objects.
They roll easily because they have little friction as they move over the ground.
Did you know a doorknob is really two wheels connected by an axle? You can’t see the axle because it’s inside the door, but it’s there!

18. Gears A gear is a wheel with teeth.
The teeth fit in between each other and turn.
When one gear turns, its teeth push against the teeth of the other gear and they both turn.
There are gears on your bike, on a can opener and on an egg beater.

19. Pulleys
A pulley is a wheel with a rope running over it. The wheel has a groove and it keeps the rope from slipping off the wheel.
A single pulley does not change the amount of force used, but it does reverse the direction of the effort.
When you pull down, the load moves up!

20. Pulleys
A movable pulley reduces the amount of force used, but it does not reverse the direction of the effort.
As the rope attached to the movable pulley is pulled up, the load moves up!
The weight of the load is distributed to the different supporting ropes. You need less force to pull the load up.

21. The 6 Simple Machines Lever Inclined Plane Pulley Wheel and Axle Wedge
Screw

22. Compound Machines