1. WORK Force acting through a distance ENERGY POWER How fast work is done Capacity to do work MACHINES Makes work easier

3. Instrument that makes work easier

7. http://www.youtube.com/watch?v=TlPWy7qW7oM Eureka video: Pulleys and Simple Machines

8. WORK • is the transfer of energy from one physical distance to another • Measured in Joules W = F x d Work = Force x Distance

9. What is Mechanical Advantage? Number of times a machine multiplies the effort force Tells how much force is gained by using machine

19. A machine makes work easier by changing the amount of force you exert, the distance over which you exert your force, or the direction in which you exert your force. • The force you exert on the machine is called the input force or the effort force. The force exerted by the machine is called the output force or the resistance force. • If you compare the input force to the output force, you can determine the advantage of using a machine. A machine’s mechanical advantage is the number of times a force exerted on a machine is multiplied by the machine.

20. TYPES OF WORK A.INPUT work that goes into the machine needs effort force

21. B.OUTPUT Work done by (out of) the machine Resistance Force

22. WORK = FORCE x DISTANCE • WORK INPUT WORK OUTPUT • INPUT = OUTPUT Change in Direction OUTPUT FORCE DISTANCE EFFORT FORCE DISTANCE Change distance overwhich force is exerted Multiply the force

23. Machines do not increase work output “Work output is never greater than work input”

24. Work in = Work out • Work input (force to move something over a distance) • Work output (force from the machine to move something over a distance) • Machines make work easier because they change either the _________ , _________ or _________of the force put into the machine.

25. Video Clips http://www.youtube.com/watch?v=yfAdmRJDKIc&feature=fvw Simple machines-pulley (Instructional guide) http://www.youtube.com/watch?v=joKbTV2QvNU&feature=related How a pulley works (simple explanation) http://www.youtube.com/watch?v=RouXygRcRC4 http://www.youtube.com/watch?v=8wyuB7jHVfg

26. Lever A bar free to pivot, or rotate about a fixed point (fulcrum) Inclined Plane A flat, slanted surface Wheel and axle Circular lever (axle is fulcrum) Pulley A wheel revolving freely around an axle Wedge Portable/moving inclined plane Screw Twisted inclined plane Gear Toothed wheel that fit into one another

27. LEVERS • Simple machines used to lift weights

29. First Class Levers An example of this type is a seesaw.

30. Second Class Lever The difference from the first class lever is that the fulcrum is on the end, instead of in the middle.

31. Third Class Lever The load is the fish; the handle end is the fulcrum.

36. INCLINED PLANE

37. Inclined Plane • A simple machine that makes it easier to move a heavy object to a higher or lower elevation. • It reduces the amount of force needed to lift the object.

39. The Egyptians used inclined planes to build the pyramids.

40. WEDGES • A wedge is a simple machine shaped like an inclined plane. • It is like a portableinclined plane.

42. SCREWS A screw is a cylinder with an inclined plane wrapped around it.

43. Archimedes’ Screw Archimedes of Syracuse, when he was in Egypt, invented a machine for pumping bilge water out of the holds of ships.

46. Larger Object (wheel) Smaller Object (axle) WHEEL AND AXLE made up of two circular objects of different sizes

48. Pulley A wheel revolving freely around an axle