1. Review work and energy Physics

2. What is the law of conservation of energy? What does it mean for this unit?

3. Energy is conserved – cannot be created nor destroyed – but can change forms Total initial energy = total final energy

4. True or false about work? A. Work is a form of energy. B. A Watt is the standard metric unit of work. C. Work is a time-based quantity; it is dependent upon how fast a force displaces an object. D. The force of friction acts upon a softball player as she makes a headfirst dive into third base. This is an example of work being done

5. Red = true A. Work is a form of energy. B. A Watt is the standard metric unit of work. C. Work is a time-based quantity; it is dependent upon how fast a force displaces an object. D. The force of friction acts upon a softball player as she makes a headfirst dive into third base. This is an example of work being done

6. True or False on Power A. Power is a time-based quantity. B. Powerful people or powerful machines are simply people or machines which always do a lot of work. C. If person A and person B do the same job but person B does it faster, then person A does more work but person B has more power

7. Red = true A. Power is a time-based quantity. B. Powerful people or powerful machines are simply people or machines which always do a lot of work. C. If person A and person B do the same job but person B does it faster, then person A does more work but person B has more power

8. True or False for Kinetic energy A. Kinetic energy is the form of mechanical energy which depends upon the position of an object. B. If an object is at rest, then it does not have any kinetic energy. C. If an object is on the ground, then it does not have any kinetic energy.

9. Red = true A. Kinetic energy is the form of mechanical energy which depends upon the position of an object. B. If an object is at rest, then it does not have any kinetic energy. C. If an object is on the ground, then it does not have any kinetic energy.

10. True or False – potential energy A. Moving objects cannot have potential energy. B. Potential energy is the energy stored in an object due to its position. C. Both gravitational and elastic potential energy are dependent upon the mass of an object. D. If the mass of an elevated object is doubled, then its gravitational potential energy will be doubled as well.

11. True are red A. Moving objects cannot have potential energy. B. Potential energy is the energy stored in an object due to its position. C. Both gravitational and elastic potential energy are dependent upon the mass of an object. D. If the mass of an elevated object is doubled, then its gravitational potential energy will be doubled as well.

13. D all have same speed RECALL: PE = KE so same height – so PE at top is max and KE is max at bottom – same total energy – so since same object the KE = 1/2mv 2 so same object has same speed at bottom Due to conservation of energy! Works going up too – if same distance and same object

14. 72kg Barry Uhm is at rest on top of a 30m hill, he then slides down the hill and goes up another hill that is 10m high. How fast is he going on top of the 10m high hill? Show energy bar chart.

15. PE + KE  PE + KE mgh + 0 = mgh + 1/2mv 2 (72kg) (9.8m/s 2 ) (30m) = (72kg) (9.8m/s 2 ) 10m) + ½ (72kg) v 2 V = 19.7m/s