1. DO NOW Prepare for Vocabulary Quiz over chapter % words Pick up notes sheet when you turn it in.

2. GET OUT YOUR PHONES

3. NOW, PUT YOUR CELL PHONES AWAY…

4. Wedge Inclined Plane Screw Wheel and Axle Lever Pulley MACHINES

5. WHAT IS A MACHINE? A machine is a device that makes work easier Remember WORK? Work is the transfer of energy that occurs when a force makes an object move. So a machine makes that transfer of energy easier.

6. MAKING WORK EASIER Work can be made easier by: 1.Increasing Force 2.Increasing Distance 3.Changing Direction

7. INCREASING FORCE You can do the same amount of work by Applying a small force over a long distance OR Applying a large force over a small distance

8. INCREASING FORCE Each complete rotation of the jack handle applies a small force over a large distance. A small force over a large distance becomes a large force over a small distance.

9. INCREASING DISTANCE Work equals force x distance so if you increase the distance, less force is needed for the same amount of work. Just lifting the dresser straight up would take more force. A machine that decreases the distance through which you exert a force increases the amount of force required.

10. CHANGING DIRECTION Some machines change the direction of the force applied. When you use a car jack, you are pushing down but the jack is pushing the car up.

11. THE WORK DONE BY MACHINES Two forces involved when a machine is used to do work. –The force applied to the machine is the EFFORT FORCE, F e. –The force applied by the machine to overcome resistance is called the RESISTANCE FORCE, F r.

12. EXAMPLES Hammer and nail –Effort force: –Resistance force: Screwdriver and paint can –Effort force: –Resistance force: Can opener –Effort force: –Resistance force:

13. TWO KINDS OF WORK You need to consider the work done by you and the work done by the machine. The work done by you on the machine is called INPUT WORK, W in. The work done by the machine is called the OUTPUT WORK, W out.

14. CONSERVING ENERGY Energy is always conserved. When you do work on the machine, you transfer energy to the machine. The machine then transfers energy to the object. A machine cannot create energy, so W out is always <W in. Energy can be lost to heat due to friction.

15. MECHANICAL ADVANTAGE The number of times a machine multiplies the effort force is the mechanical advantage (MA) of the machine. Divide the resistance force by the effort force.

16. EXAMPLE Miniblinds –You pull down on the cord and the blinds go up the same amount. –Effort force = resistance force –MA = 1

17. EXAMPLE

18. Machines are a “give and take relationship.” If you get your force multiplied, then you must go a greater distance. Watch for this in all Simple machines :

19. WATCH Mechanical Advantage

20. TO DO Do the four Mechanical Advantage problems.

21. SIMPLE MACHINES

22. WHY? Simple machines are useful because they can make a physical job easier by changing the magnitude or the direction of the force exerted to do work.

23. Have you ever tried to unscrew a nut, bolt, or screw from something with your bare hands and discovered that it was just too tight to loosen even if you had a good grip?

25. You got the proper tool, such as a screw driver or wrench, and unscrewed it!

26. Why is it that it's so easy to unscrew with a tool when you can't with your bare hands?

27. The wrench and screw driver are examples of a wheel and axle, where the screw or bolt is the axle and the handle is the wheel. The tool makes the job easier by changing the amount of the force you exert. Axle Wheel

28. All of the simple machines can be used for thousands of jobs from lifting a 500-pound weight to making a boat go. The reason why these machines are so special is because they make difficult tasks much easier.

30. Fulcrum Lever Load Click Here to Learn More

31. Click on the dude to learn more.

32. A screw is an inclined plane wrapped around a post. Click on the light bulb to learn more.

33. Two inclined planes make a wedge. Try to catch the saw to learn more.

34. Axle Wheel Click on the windmill to learn more.

35. Wheel Rope This box is easier to lift because of the pulley. Click on it to learn more.

36. Have you learned it all yet? Let’s look at a worksheet to see. Click Here

37. Click above

38. Now it’s time to link to Inspiration. When you get there, all of the simple machines are shown. Create some clouds around each picture and add some examples for each simple machine. Click below to begin.