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Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
Work v Power
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Work v Power

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Work vs Power lesson

Work vs Power lesson

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  • 1. Work v. Power <ul><li>Date: October 30, 2006 </li></ul><ul><li>Objective: Understand the difference between work and power. </li></ul><ul><li>A-Team: </li></ul><ul><li>Homework: Power Worksheet </li></ul><ul><li>Catalyst: Why does a feather fall to the ground slower than an apple on Earth? </li></ul>
  • 2. Time is Up <ul><li>(Five minutes starts right at the tardy bell. We have to maximize our time!) </li></ul>
  • 3. Housekeeping <ul><li>Grades grades grades </li></ul><ul><ul><li>Check your actual average posted by doorway on your way out of class </li></ul></ul><ul><ul><li>Compare to your grade received </li></ul></ul><ul><ul><li>No “bumps” in quarter 2. </li></ul></ul>
  • 4. Housekeeping <ul><li>Website </li></ul><ul><ul><li>Updated with resources, slides, worksheets </li></ul></ul><ul><ul><li>Weekly “online extra” question. </li></ul></ul><ul><ul><ul><li>Way to add points to your grade every week. </li></ul></ul></ul><ul><ul><ul><li>Due on Monday of following week. </li></ul></ul></ul><ul><ul><li>Extra Credit Project posted </li></ul></ul><ul><ul><li>www.workhardgetsmart.com </li></ul></ul>
  • 5. Housekeeping <ul><li>Special Opportunity </li></ul><ul><ul><li>Enter to win… trip to an invite-only screening of a new OmniMax film this Thursday evening </li></ul></ul><ul><ul><li>Transportation provided by me if needed </li></ul></ul><ul><ul><li>Entries (one paragraph) due by end of day on Tuesday. </li></ul></ul><ul><ul><ul><li>Relate to your progress toward big goal. </li></ul></ul></ul>
  • 6. Housekeeping <ul><li>Results from Friday’s CFU </li></ul><ul><ul><li>P: A,B,C,D,F </li></ul></ul><ul><ul><li>1: 2,2,0,0,4 </li></ul></ul><ul><ul><li>2: 2,1,0,0,1 </li></ul></ul><ul><ul><li>3: 3,1,1,1,5 </li></ul></ul><ul><ul><li>5: 0,9,2,4,6 </li></ul></ul><ul><ul><li>6: 1,0,0,2,3 </li></ul></ul><ul><ul><li>7: 0,0,1,5,6 </li></ul></ul><ul><ul><li>T: 8,13,4,12,25 </li></ul></ul>37 of 62 (60%) of students got a D or F
  • 7. Housekeeping <ul><li>How to improve CFU scores </li></ul><ul><ul><li>Come to class // stay out of ISS </li></ul></ul><ul><ul><ul><li>If you miss a day, you miss a lot. </li></ul></ul></ul><ul><ul><ul><li>We’re learning together, not just out of the book </li></ul></ul></ul><ul><ul><li>Do the homework </li></ul></ul><ul><ul><ul><li>It reinforces, extends </li></ul></ul></ul><ul><ul><ul><li>Allows opportunities to practice using ideas before CFU </li></ul></ul></ul><ul><ul><li>Ask for help </li></ul></ul><ul><ul><ul><li>Before or after school, I’m available </li></ul></ul></ul>
  • 8. Housekeeping <ul><li>Speaking of doing homework </li></ul><ul><ul><li>67 People with nothing turned in! </li></ul></ul><ul><ul><li>YIKES  0/8 points </li></ul></ul><ul><li>Prime time for the extra credit project </li></ul>
  • 9. Catalyst <ul><li>Q: Why does a feather fall to the ground slower than an apple on Earth? </li></ul><ul><li>A: There is air resistance on Earth. But if you do the experiment in a vacuum, it will happen at the same time. </li></ul><ul><ul><li>http://www.hep.uiuc.edu/home/mats/WCIA/wcia_030129_1.wmv </li></ul></ul>
  • 10. Rinse, Wash, Repeat <ul><li>Force is a push or a pull </li></ul><ul><li>Measured in Newtons </li></ul>
  • 11. Work <ul><li>Work is applying a force that causes a change in position or motion of an object in the direction of the force </li></ul><ul><li>When work is done, energy is transferred </li></ul><ul><li>Work is defined by an equation </li></ul><ul><ul><li>Work = force x distance </li></ul></ul><ul><ul><li>W = F x d </li></ul></ul><ul><li>Work is measured in joules (J) </li></ul>
  • 12. Is it work? <ul><li>Rahman pushes up against the wall and becomes exhausted. </li></ul><ul><li>Markeisha’s book falls off a table and free falls to the ground. </li></ul><ul><li>Nikki carries her backpack above her head through the hallway. </li></ul><ul><li>Derrick’s rocket flies upward through the air. </li></ul>
  • 13. Is it work? <ul><li>Rahman pushes up against the wall and becomes exhausted. NO </li></ul><ul><li>Markeisha’s book falls off a table and free falls to the ground. YES </li></ul><ul><li>Nikki carries her backpack above her head through the hallway. NO </li></ul><ul><li>Derrick’s rocket flies upward through the air. YES </li></ul>
  • 14. Power <ul><li>Measuring power is common </li></ul><ul><li>All those car commercials </li></ul><ul><ul><li>The 2005 model accelerates from 0-60 in 12 seconds </li></ul></ul><ul><ul><li>The 2006 model accelerates from 0-60 in 8 seconds </li></ul></ul><ul><ul><li>Which one is more “powerful?” </li></ul></ul><ul><ul><ul><li>The 2006 model </li></ul></ul></ul><ul><ul><ul><li>It does the same amount of work in less time </li></ul></ul></ul>
  • 15. Power <ul><li>Power measures the rate (how fast) work is done </li></ul><ul><ul><li>“The rate” means that there is time involved </li></ul></ul><ul><li>Power is defined by an equation </li></ul><ul><ul><li>Power = work / time </li></ul></ul><ul><ul><li>P = W / t </li></ul></ul><ul><li>Power is measured in watts (W) </li></ul><ul><ul><li>The power required to do 1 joule of work in 1 second </li></ul></ul><ul><li>IMPORTANT: Don’t get confused by the two W’s </li></ul>
  • 16. How it’s all connected <ul><li>Power = Work / time </li></ul><ul><li>Work = force x displacement </li></ul><ul><li>Velocity = displacement / time </li></ul><ul><li>Mix and match </li></ul><ul><ul><li>Power = (force x displacement) / time </li></ul></ul><ul><ul><li>Or </li></ul></ul><ul><ul><li>Power = force x (displacement / time) </li></ul></ul><ul><ul><li>So </li></ul></ul><ul><ul><li>Power = force x velocity </li></ul></ul><ul><li>This makes sense: a powerful machine is strong and fast </li></ul><ul><ul><li>The best lineman in football is strong and fast </li></ul></ul>
  • 17. Check your head <ul><li>Two students, Will and Ben, are in the weightlifting room. Will lifts the 100-pound barbell over his head 10 times in one minute; Ben lifts the 100-pound barbell over his head 10 times in 10 seconds. Which student does the most work? Which student delivers the most power? Explain your answers. </li></ul><ul><li>Turn in your answer on a clean sheet of paper on your way out. </li></ul>

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