1. How Machines Work

2. Silent Seven What is friction? Give an example and state what type of friction it is. When potential energy is converted to kinetic energy, what is always left?

3. Work and Power Work is the amount of force applied over a given distance Power is how quickly work is done Simple machines affect the amount of force we apply an give us a mechanical advantage for the amount of work we have to complete

4. Machine A machine is a device that allows you to do work that is easier by changing at least one of three factors: The amount of force you exert The distance the forces is exerted The direction in which you exert the force

5. Input and Output Work Input work = input force * input distance Input force: the force you exert on a machine Input distance: the distance the input force moves the object Output work= output force * output distance Output force: the force the machine exerts on object Output distance: the distance the output force moves the object

6. Input and Output Work Output WORK of the machine CANNOT be greater than the input work of the person doing the work If your were digging the hole, which is doing more work, your hands or the shovel? However… The output FORCE can be greater, less than or equal to the input FORCE

7. Input and Output Work ForceDistanceDirectionExampleHow? Output Force is greater than input force Input distance is greater than output distance Direction of the force remains the same Pushing a box up a ramp You push the box with less force up the ramp than if you were to lift the ramp Input force is greater than output force Output distance is greater than input distance Direction of the force remains the same Hitting a baseball with a bat You move your arms a short distance and the bat moves the ball a much larger distance Input force equals output force Input distance equals output distance Direction of force changes Lifting weights on a machine You change the direction of your force but the distance traveled or the weight does not change

9. Mechanical Advantage

10. What happed to the forces? How was work made easier? Mechanical Advantage Example the output force is greater than the input force The force increased greater than 1 N input force is greater than the output force The distance increased Less than 1 N input force equals the output force The direction changed 1 N

11. Efficiency

12. Calculating Efficiency

13. Independent Practice In your seats complete the following sheet. For homework, complete the following textbook problems: Pg. 419 lab, 2abc, 3ab 433 lab, 3a 437 1-10 Whatever you do not finish is homework

14. Mechanical Advantage

15. Practice

16. Buzzer Beater 1. What is mechanical advantage? 2. What is efficiency? 3. To lift a television, you can apply a force of 50 N to a wedge. The wedge applies a force of 480 N to the weed. What is the mechanical advantage of the wedge? A. 10 N B. 12 N C. 15 N D. 22 N 4. If the input distance was 0.5 meters and the output distance was 1 meter to move the same TV what is the input work and the output work? 5. Using the input and output work for the same TV, what was the efficiency of the wedge?