The document discusses different types of energy including mechanical energy, potential energy, and kinetic energy. It defines work as force multiplied by distance and explains that more work is done when lifting heavier objects over greater distances. Power is defined as the rate of doing work over time and is measured in Watts. The document also covers the law of conservation of energy and efficiency.

1. ENERGY By

2. Work Formula: Work= Force * Distance W=FD

3. Example of Work Lifting a load against Earth’s gravitational pull For example, this man is attempting to lift a box off of the ground against the pull of gravity.

4. Continued The heavier the load and the higher we lift the object, the more work we do. Superman here is doing quite the amount of work because he is lifting a very heavy mass, while at the same time lifting it high into the air.

5. Example 2 Weight lifting Work is done when lifting a barbell. The higher the mass, and the higher the barbell is lifted, the more work is done.

6. Hold up Contrary to the past two slides, though the amount of work done depends on the displacement and the mass of the object, if a object is standing still, no work is being done

7. Explanation Ok lets go back to superman, when he lifted the car above his head, he did a tremendous amount of work. However, now that the car is being held idly above his head, he is doing zero work.

8. Categories Work is generally separated into two different categories

9. 1 Work done against another force For example: an archer stretching his bow and arrow

10. 2 Work done to change the speed of an object Example: bringing a car in motion to a stop.

11. Unit of Measurement Joule 1 Newton exerted over 1 meter That guy is James Joule, the guy the unit is named after

12. Sample Question How much work is done on a 100N boulder that you carry horizontally across a 10m room? CLICK FOR ANSWER

13. Power Formula: Power = Work divided by Time P=W/t

14. Power Power is the measure of how long it takes you to do work. Example: How long it takes to run up a flight of stairs

15. Unit of Measurement Watts 1 Joule in 1 sec That’s James Watt

16. Sample Question What power is expanded if you lift a 100N boulder a distance of 1 m in a time of 1 s CLICK FOR ANSWER

17. Types of Energy

18. Mechanical Mechanical energy is the energy due to the position of something, or the movement of something There are two types of mechanical energy

19. Potential Energy Potential energy is stored energy in an object. Formula: PE=mgh Example: in a stretched rubber-band, energy is stored in the rubber band then used when released.

20. Kinetic Energy Kinetic energy is energy used in motion. Formula: 1/2(m)(v)(v) Example: A runner is expanding kinetic energy.

21. Sample Question When the brakes of a motorcycle traveling at 60km/h become locked, how much further than the motorcycle skid than if it travels at 20km/h? CLICK FOR ANSWER

22. Law of Conservation of Energy Energy cannot be created or destroyed. It can be transformed from one form into another, but the total amount of energy never changes

23. Efficiency Useful work output Total work input That fraction will always be less than one.

24. Answer Power= 100J/1s=100W 100 Watts CLICK TO GO BACK TO PREVIOUS SLIDE

25. Answer 2 You do not work on the boulder moved horizontally, because you apply no force (except for the tiny bit to start and stop it) in its direction of motion. CLICK TO GO BACK

26. Answer 3 Nine times farther; the motorcycle has nine times as much kinetic energy when it travels three times as fast. CLICK TO GO BACK