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# What is energy2010

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### What is energy2010

1. 1. Warm up…<br />How are energy and work related?<br />
2. 2. ENERGY<br />Chapter 5 Section 1<br />
3. 3. Energy is the ability to do work<br />Work is the transfer of energy<br />Force moves an object<br />Measured in Joules (J)<br />What are some things that make a job feel like more work?<br />Energy…<br />Force<br />
4. 4. How are energy and work being done during this tennis match?<br />
5. 5. How are energy and work being done during a golf tournament?<br />
6. 6. Energy of MOTION<br />Depends on speed and mass<br />KE = mv2<br /> 2<br />LOOK at the formula…<br />Which has a greater effect on KE, <br />mass or speed?<br />Why/how do you know?<br />Kinetic Energy <br />
7. 7. INDEX CARD<br />ENERGY UNIT FORMULAS…<br />KE = mv2<br /> 2<br />
8. 8. Which has more KE-the red car or green car? Explain.<br />
9. 9. Which has more KE-the red car or truck? Explain. <br />
10. 10. A snail with a mass of 5 g traveling at 0.014 m/s has a KE of 0.00000048 J!<br />An 18-wheel truck traveling at 44 mi/h has a KE of 2,200 J!<br />Weird Science...<br />
11. 11. Provide a caption for your work/energy picture <br />Label any area where work is being done (you should have at least 2 places where you have shown some work)<br />Put your name and class period on the back of your illustration<br />
12. 12. On the back of your paper, please explain the following in a short paragraph:<br />-Energy<br />-Work<br />-How your picture demonstrates these 2 ideas<br />
13. 13. Warm up…<br />What is your hypothesis for the rubber band racers?<br />What is the independent variable? <br />The dependent?<br />
14. 14. Rubber Band Racers…<br />Build your car quickly; divide the jobs and work as a team<br />Begin with 1 energy unit (1 winding) and run 3 trials for each number of windings; collect data<br />Average the data for each energy unit<br />Graph the average data for distance vs the energy units<br />YOU MUST MEASURE DISTANCE IN METRIC<br />
15. 15. Warm up…<br />Was your hypothesis for your racer correct? Why?<br />What is a good title for the graph you will create with this data?<br />
16. 16. Warm up…<br />What are the 2 factors that determine the KE of an object?<br />
17. 17. KE FACTORS DEMO…<br />Copy the chart below into your notes.<br />Using the setup described on the paper at your table, launch the lid with the discs. Record your data.<br />
18. 18. Quickly graph your data.<br />Answer the 3 questions below:<br />What was the trend you observed as you increased the # of washers you launched?<br />Using your graph, what would the distance have been for 2 washers?<br />What is the independent variable in this quick demo? Why/Explain.<br />
19. 19. KE PROBLEMS…<br />1. What is the kinetic energy of a car that has a mass of 1,200 kg and is moving at a speed of 20 m/s?<br />2. What is the kinetic energy of a car that has a mass of 2,400 kg and is moving at a speed of 20 m/s?<br />3. How does the kinetic energy of the 2 cars above compare? What do you notice?<br />
20. 20. Cool down…<br />What are the 2 factors that determine the KE of an object?<br />What is the formula for KE?<br />Which factor has a greater impact on KE?<br />
21. 21. Warm up…<br />What are the 2 factors that determine the KE of an object?<br />What is the formula for KE?<br />Which factor has a greater impact on KE?<br />
22. 22. Energy of POSITION or SHAPE<br />Depends on weight and height<br />The amount of work done to get object in that position.<br />GPE = weight x height<br />What’s the difference between <br />weight & mass?<br />Potential Energy<br />
23. 23. INDEX CARD<br />ENERGY UNIT FORMULAS…<br />KE = mv2<br /> 2<br />GPE = weight x height<br />
24. 24. Diver A <br />450 N<br />Diver B <br />500 N<br />Does Diver A or B have more GPE? <br />Which Diver did more work?<br />
25. 25. Does Diver C or D have more GPE? <br />Which Diver did more work?<br />Diver C <br />550 N<br />Diver D <br />550 N<br />
26. 26. Diver C <br />550 N<br />Diver A <br />450 N<br />Diver B <br />500 N<br />Diver D <br />550 N<br />Which Diver did the most work?<br />
27. 27. GPE PROBLEMS…<br />1. What is the gravitational potential energy of a book with a weight of 13 N at a height of 1.5 m off the ground?<br />2. What is the gravitational potential energy of a cat that weighs 40 N standing on a table that is 0.8 m above the ground?<br />
28. 28. The sum of the kinetic and potential energy. <br />ME = KE + PE<br />Mechanical Energy<br />
29. 29. INDEX CARD<br />ENERGY UNIT FORMULAS…<br />KE = mv2<br /> 2<br />GPE = weight x height<br />ME = KE + PE<br />
30. 30. Weight = 200 N<br />Mass = 20 kg<br />What is GPE of the car?<br />What is KE of the car?<br />Speed = 0 m/s<br />Height = 5 m<br />
31. 31. Weight = 200 N<br />Mass = 20 kg<br />GPE = Wt * Ht = 200 * 5 GPE = 1,000 J<br />KE = m * v2 / 2 = 20 *02 / 2 <br /> KE = 0 J<br />Speed = 0 m/s<br />Height = 5 m<br />
32. 32. Warm up…<br />What is the difference between GPE and KE?<br />Why do we use mass for KE and weight for GPE?<br />
33. 33. Weight = 200 N<br />Mass = 20 kg<br />What is the ME for this system?<br />Speed = 0 m/s<br />Height = 5 m<br />
34. 34. Weight = 200 N<br />Mass = 20 kg<br />ME = KE + PE<br />ME = 0J + 1,000J<br />ME = 1,000J<br />Speed = 0 m/s<br />Height = 5 m<br />
35. 35. Weight = 200 N<br />Mass = 20 kg<br />What is GPE of the car now?<br />What is KE of the car now?<br />Height = 5 m<br />Speed = 10 m/s<br />
36. 36. Weight = 200 N<br />Mass = 20 kg<br />GPE = Wt * Ht = 200 * 0 GPE = 0 J<br />KE = m * v2 / 2 = 20 *102 / 2 <br /> KE = 1,000 J<br />Height = 5 m<br />Speed = 10 m/s<br />
37. 37. Warm up…<br />What kind of energy is found in a stretched rubber band? Explain.<br />What kind of energy in found in a rubber band that has been released? Explain.<br />
38. 38. Warm up…<br />On a ramp, where would you find the most potential energy?<br />Where would you find the most kinetic energy?<br />
39. 39. Weight = 200 N<br />Mass = 20 kg<br />What is the ME for this system?<br />Height = 5 m<br />Speed = 10 m/s<br />
40. 40. Weight = 200 N<br />Mass = 20 kg<br />ME = KE + PE<br />ME = 1,000J + 0J<br />ME = 1,000J<br />Height = 5 m<br />Speed = 10 m/s<br />
41. 41. GPE = 1,000J<br />KE = 0J<br />
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47. 47. GPE = 0J<br />KE = 1,000J<br />
48. 48. What’s happening to the GPE as he rolls down the hill?<br />Height decreases so GPE decreases<br />
49. 49. What’s happening to the KE as he rolls down the hill?<br />Speed increases so KE increases<br />
50. 50. If the ME for this system is 1,000J, what would expect the GPE and KE to be at the half way point?<br />ME = 500J + 500J<br />
51. 51. More KE, less GPE<br />
52. 52. Almost all KE now<br />
53. 53. GPE = 0J<br />KE = 1,000J<br />850J<br />Wait a minute, Mrs. Lock! When we tested this in the lab, the KE at the bottom was LESS than the GPE at the top. WHY???<br />Where did the energy go?<br />
54. 54. GPE = 0J<br />KE = 1,000J<br />850J<br />Some energy was changed into heat and sound as the car wheels rubbed against the ramp.<br />ME = KE + PE + friction!<br />
55. 55. Warm up…<br />How does a pendulum show KE and GPE?<br />
56. 56. Warm up…<br />What is the GPE at Point A?<br />What is the ME for the picture?<br />What is the GPE at Point B?<br />What is the approximate KE at Point B?<br />100 N<br />20 M<br />10 M<br />
57. 57. Warm up…<br />How does a pendulum show energy conversions?<br />What is the law of Conservation of Energy?<br />
58. 58. A Pendulum Experiment<br />Info: <br />We want to see what affects the time a pendulum takes to swing. Time period is the time for a full swing (forward and backward). <br />Question: <br />How does length of the pendulum affect its time period?<br />
59. 59. Question: <br />How does length of the pendulum affect its time period? <br />Write your hypothesis using the question above. Remember it MUST be an “If…then…” statement. <br />Use an independent and a dependent variable<br />
60. 60. Data: <br />Copy the chart below: <br />
61. 61. Steps: <br />1. Measure the length of string <br />2. Measure the time for 20 full swings <br />3. Divide by 20 to find the time for 1 swing. <br />4. Repeat this for 9 additional string lengths<br />5. Graph the data (independent variable on the x-axis, dependent on the y-axis)<br />
62. 62. Warm up…<br />What is happening to energy at the top of a jump on a trampoline?<br />At the bottom?<br />
63. 63. Steps: <br />Graph the data (independent variable on the x-axis, dependent on the y-axis)<br />Respond to the following on your graph paper in a good paragraph:<br /><ul><li>Was your hypothesis correct or incorrect? Why? Explain how energy is transferred in a pendulum. How does the Law of Conservation of Energy Apply to a pendulum?</li></li></ul><li>Warm up…<br />Describe the energy conversions that happen as a skier goes down the slope.<br />Does ME change along the way? Explain.<br />
64. 64. Pop Quiz<br />Wt=50N<br />A.<br />B.<br />C.<br />What is the KE at point A?<br />What is the PE at point A?<br />What is the ME at point A?<br />What is the PE at point B?<br />Use ME(and PE) to find the KE at point C.<br />Show work on back <br />Put answers on front<br />