2. Tuesday, September 29, 2009 In olden days, something was only considered “doing work” if you were getting tired or sweaty doing it. Make up a definition for this type of work using what we know about energy (use the word energy) In olden days, something was only considered “doing work” if you were getting tired or sweaty doing it. Make up a definition for this type of work using what we know about energy (use the word energy) HW: Read 6.1 in your book, answer 3 questions Read 6.4, answer 3 questions Read 6.5, answer 3 questions

3. As an object falls, its potential energy decreases. What happens to its kinetic energy? 1. It also decreases 2. It increases 3. It remains the same

4. To determine potential energy of an object due to gravity, you need which of the following? 1. Height 2. Force 3. Weight

5. If we double the velocity of an object, what happens to its kinetic energy? 1. It also doubles 2. It quadruples 3. It triples 4. It remains the same

6. Work Two things needed for work to be done: 1.The application of a force 2.The movement of something by that force Work = force x distance What is needed to do twice the work? 5 m 12 N

7. Work Work = force x distance What is needed to do twice the work?

8. Work Work = force x distance The unit of measurement for work combines force and distance. The newton-meter (N*m) or joule.

9. An athlete lifts a 1.0-Newton weight 2.00 meters. How much work did they do? 1. 2.0 Watts 2. 2.0 Joules 3. 1.0 Watts 4. 1.0 Joules 5. 4.0 Watts 6. 4.0 Joules 7..5 Watts 8..5 Joules

10. An object with a weight of 2.00 N falls from a cliff that is 35.0 ft? Calculate its potential energy. 1. 720 J 2. 686 J 3. 70.0 J 4. 6.86 J

11. An object with a mass of 3.00 kg falls from a cliff that is 40.0 m? Calculate its potential energy. 1. 1176 J 2. 120 J 3. 1200 J

12. An object with a mass of 20.00 kg is speeding at 40.0 m/s? Calculate its kinetic energy. 1. 400 J 2. 32000 J 3. 16000 J

13. An object with a mass of 62.5 kg is speeding at 22 m/s? Calculate its kinetic energy. 1. 15125 J 2. 687.5 J 3. 30250 J

14. Power Power is the rate at which work is done. Power is the rate at which work is done. Unit of power: joule per second or watt. Unit of power: joule per second or watt. One watt (W) is expended when one joule of work is done over one second. Kilowatt (kW) = 1000 watts Megawatt (MW)= 1,000,000 watts 1 hp =.75 kW 134 hp = 100 kW