Simple Machines

1. Simple Machines The need to know.

2. Inclined Plane • What is an inclined plane? • A ramp that moves an object from a lower to a higher level

3. How does an inclined plane make work easier? • By spreading the work over a longer distance • How does an inclined plane give us a mechanical advantage? • Allows us to use less effort to raise or move an object

4. Inclined Plane Examples

5. Inclined Plane Video • You do not need to know about the measurements and newtons. • Inclined Plane Video

6. Inclined Plane Experiment • Objective: To show how the steepness of an inclined plane can affect the amount of force necessary to do work. • Procedure: • 1. Make a stack of books about six inches high. Form two ramps of different lengths by leaning a ruler and a yardstick up against the top of the stack. • 2. Loop a rubber band through the eye screw in the end of a wooden block. Place the block at the end of one ramp with the rubber band end toward the ramp. • 3. Pull the block up one ramp. Try again using the other ramp. • 4. Notice how much the rubber band stretches. How does the steepness of the ramp affect the rubber band? If you had to move a heavy piano into a moving van, would you rather have a short, steep ramp or a long, less steep ramp? The work to be done is the same in each case. Since work = force x distance, moving the piano into the van over a longer distance means less force is required.

7. Wedge • What is a wedge? • A wedge is one or two inclined planes put together • It may lift, pierce or cut an object. It can also fasten two objects together

8. How does an wedge give us a mechanical advantage? • Changes the direction of force

9. Wedge Examples – What does each do? Pierce, cut, lift or fasten? Pierce Cut Cut Cut Lift Fasten

10. Wedge Experiment • Give each child a large slice of an apple. • Have them take one bite using their incisors (front teeth). Have take a second bite using their back teeth (pre-molars or molars). Which was easier? Your sharp incisors are like wedges. They slice into and divide the apple slice. Your pre-molars are like those square blocks. As children finishing eating their apple slices • Let them each have a turn cutting other apple slices with a kitchen knife/butter knife and a paring knife. Which is easier to use? The thinner the tip/sharper the blade of a wedge, the better it will be at exerting equal pressure in both directions and slicing through what you want to cut through. That's why it's best to sharpen knifes, plows, hoes, etc.

11. Screw • What is a screw? • An inclined plane wrapped around a core (spiral) • Used to fasten objects or lift heavy objects

12. How does a screw make work easier? • By spreading the work out over a longer distance • How does a screw give us a mechanical advantage? • Allowing us to use less effort to fasten or raise objects

13. Screw Examples

14. Screw Experiments • Screw Experiments

15. Wedge and Screw Video • Wedge and Screw Video

16. Lever • What is a lever? • A bar that rests on and turns around a point • Levers lift or move objects • 3 parts (fulcrum=turning point, load=thing you want to move, effort=force you apply to a part of the lever)

17. How does a lever make work easier? • It puts some of the work on the fulcrum • The closer the fulcrum is to the load the easier it is to lift or move the load • How does a lever give us a mechanical advantage? • Allows us to use less force and to change the direction of force

18. Lever Examples – Can you find the load, effort and fulcrum? E L E E L F F L E L F F F L E F L L E L E E F F

19. Lever Experiment • Try this experiment! • Lever Experiment

20. Lever Video • Lever Video