1. Directions Click “Slideshow” the “From Beginning” to view this slide show properly. Click on links to watch clips. Take proper notes as you go.

2. Fixed and Moveable Pulley Systems Movable

3. Discuss What is a simple machine? A: a device that changes the direction or magnitude of force. Why do you think simple machines were invented? How do they help us? A: they make WORK EASIER If I push with all my force on my lab table is work being done? A: NO! because nothing is moving so no work is done. Click HereClick Here and log in with U.N. “harpool” and P.W. “longhorns” to learn about WORK.

4. Practice! If I push with 100N of force on my lab table but it doesn’t move… Force x Distance = Work 100N x 0m = 0 joules No work was done! If I push on my chair with 10N of force and it rolls 2m how much work was done? Force x Distance = Work 10N x 2m = 20 joules of work was done!

5. Introduction of Pulleys Watch ThisWatch This short introduction on Pulleys.

6. The fixed pulley is a pulley that is attached to a structure and does not move. It’s main purpose is to change the direction of the force needed to lift a load. A force is exerted downward in order to lift the load upward. The effort force needed does not change. Notes - Fixed Pulley

7. Here is what they look like.

8. ????? 1.Does it take less force to lift the load with the fixed pulley or without a pulley? A. The force needed to lift a load with the fixed pulley is the same as without a pulley. 2.With a fixed pulley, how is the direction of the force needed to lift the load different than without the pulley? A. The force is in the opposite direction to the direction the load moves. The force goes down and the load goes up.

9. Notes - Movable Pulley In a movable pulley system, the pulley supports the load and is not fixed in place. In the movable pulley system, the force is applied in the same direction that the load moves. However, it does require less force to move the load than without using a pulley. The trade off is that it has to be pulled a longer distance.

10. Here is what they look like.

11. 3.Does it take less force to lift the load with the moveable pulley or without any pulley? A. The force needed to lift a load with a movable pulley is less than the force needed without a pulley. 4.With a movable pulley, how is the direction of the force needed to lift the load different than without the pulley? A. The force is in the same direction as the load moves. The force is up and the load moves up. This is the same results without the pulley. ?????

12. Summary A fixed pulley makes work easier because you can pull down instead of pushing something up. A movable pulley needs less effort to lift a load BUT requires it to be pulled a longer distance. If multiple pulleys were combined, what would be the result?!? A.A pulley system that would change the direction of the load and decrease the force needed. Watch This Review!!!