1. Machines Making Work Easier

2. What Is A Machine? A machine is a device that makes work easier Examples 1. Doorknob 2. Pencil Sharpener 3. Knife 4. Crow Bar 5. Axe

3. Simple Machines Simple machines are devices that do work with only one movement There are six types of simple machines: 1. Levers 2. Pulleys 3. Wheel and axle 4. Inclined plane 5. Wedge 6. Screw

4. Pictures

5. Advantages of Simple Machines They help us overcome friction and gravity A crowbar could help us move a heavy rock or pry the lid off a wooden crate Machines make work easier by changing the force you exert in size, direction or both

6. Effort and Resistance Forces The force applied to the machine is called the effort force (F e ) The force applied by the machine to overcome resistance is called the resistance force (F r )

7. Forces cont. Sketch

8. Two Kinds of Work There is work done on the machine (W in ) There is also work done by the machine (W out ) W in =F e xd e W out =F r xd r

9. Ideal Machine If there was a perfect machine with out energy being lost to friction and heat then work input would equal work output perpetual machines - Google Search

10. The Lever A lever is a simple machine that consists of three parts: 1. An effort arm 2. A Resistance arm 3. A fulcrum

11. Sketch in Notes Fulcrum Effort Arm Resistance Arm

12. Levers There are three kinds of levers 1. 1 st class 2. 2 nd Class 3. 3 rd Class

13. 1 st Class Lever The 1 st class lever has the fulcrum in the middle of the two arms Examples are the see-saw, can openers, and scissors

14. Sketch

15. 2 nd Class Levers 2 nd class levers have the resistance and effort arms on one end, and the fulcrum on the other. The resistance is in the middle here

16. Sketch

17. 3 rd Class Levers The 3 rd class has the fulcrum on one end and the arms on the other, except reversed. Now the effort arm is in the middle

18. Sketch

19. Pulley’s A pulley is like a 1 st class lever There is a fulcrum in the middle (the wheel) and a resistance rope and effort rope Pulleys can be fixed or movable

20. Fixed pulley

21. Movable Pulley

22. Block and Tackle

23. Compound Machines A machine made up of several simple machines make up a compound machine Examples are a bicycle, a lawnmower, or a pencil sharpener