1. Simple & Compound Machines: By: Mr. Manning

2. What is a Machine again…?  A machine is a device that helps make work easier.  A machine makes work easier by changing the size or direction of a force.

3. Types of Machines:  All machines are made from the following six simple machines:  Lever  Inclined plane  Wedge  Screw  Wheel & Axle  Pulley

4. Continued:  You’ve seen a couple of these machines already- a screwdriver can be used as a lever, and a ramp onto the highway as an inclined plane.  The Human body uses simple machines.  For example, muscles and bones form levers.

5. Levers:  A lever is a simple machine consisting of a bar that pivots at a fixed point, called a fulcrum.  Levers are used to apply a force to a load.  There are three classes of levers, based on the locations of the fulcrum, the load, and the input force.  A hammer being used to remove a nail from a piece of wood is a lever.

6. Lever: (1:14)

7. Classes of Levers:  An example of a first class lever can be the claw side of a hammer removing a nail, two children on a see-saw, or a woman kayaking.  An example of a second class lever is a farmer lifting and pushing a wheel barrow full of soil.  An example of a third class lever can be a girl curling a barbell at the gym, or a carpenter hammering a nail into a table top.

8. Classes of Levers: (2:21)

9. Inclined Planes:  An inclined plane is a simple machine that is a straight, slanted surface.  A ramp is an example of an inclined plane.  The Egyptians used inclined planes a lot to move the heavy materials needed to construct the Great Pyramids.  An inclined plane does not reduce the amount of work because the object has to travel a greater distance, but the work is easier. (example sliding, rather than lifting a piano into a truck)

10. Inclined Planes: (2:27)

11. Wedges:  A wedge is a double inclined plane that moves.  A knife, for example, is an inclined that plane that makes task easier like cutting a cold sweet watermelon on a hot day.  Wedges allow you to exert force over an increased distance.  The greater the distance you move the wedge, the greater the force it applies on the object.

12. Wedges: (2:02)

13. Screw:  A screw is an inclined plane that is wrapped in a spiral.  When a screw is rotated, a small force is applied over the long distance along the inclined plane of the screw.  In other words, you apply a small input force over a large distance, while the screw exerts a large output force over a small distance.

14. IS THAT A FACT!  Both a jar lid and the top of a jar are screws. The ridges on the jar and on the lid act as screws, holding the jar and the lid together.

15. Screw: (2:54)

16. Wheel & Axle:  Did you know that when you turn a doorknob you are using a machine?  A doorknob is an example of a wheel and axle, a simple machine consisting of two circular objects of different sizes.  Examples: fishing reel handle, door knob, wrench, ferris wheel, screwdriver, steering wheel, etc.

17. Continued:  When a small input force is applied to the wheel, it rotates through a circular distance.  As the wheel turns, so does the axle. But because the axle is smaller than the wheel, it rotates through a smaller distance, which makes the output force larger than the input force.

18. Wheel & Axle: (1:35)

19. Pulley:  A pulley is a simple machine consisting of a grooved wheel that holds a rope or a cable.  A load is attached to one end of a rope, and an input force is applied to the other end.  There are two kinds of pulleys- fixed and movable, which can combine to form a block and tackle.

20. Pulley: (1:33)

21. Continued:  A fixed pulley only changes the direction of a force.  Example: an Elevator  A movable pulley is attached to the object as it is moved.  A block and tackle uses a combination of pulleys, like on a large crane used to lift extremely heavy objects.

22. Movable & Fixed Pulley:

23. Compound Machine:  Did you know that you are surrounded by machines?  Most of the machines in the world are compound machines, machines that are made of two or more simple machines.  Example: A can opener is composed of a lever, wedge, and wheel & axle.

24. Compound Machine: (2:51)