11-27-06

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11-27-06

  1. 1. November 27, 2006 <ul><li>Objective: SWBAT explain why a perpetual motion machine is impossible </li></ul><ul><li>A-Team: </li></ul><ul><li>Homework: Bring three questions in of things you “don’t understand” from last unit </li></ul><ul><li>Catalyst: A ball is rolling across the floor. How much KE? PE? (some, none, lots) </li></ul>
  2. 2. Catalyst <ul><li>Q: A ball is rolling across the floor. How much KE? PE? (some, none, lots) </li></ul><ul><li>A: </li></ul><ul><ul><li>KE – lots  it’s moving </li></ul></ul><ul><ul><li>PE – none  it has no height from ground </li></ul></ul>
  3. 3. Group by ____ <ul><li>Three minutes to come up with the best answer: </li></ul><ul><ul><li>Machines are supposed to help people make their jobs easier. But the work that a machine does is always less than the work that you must put into it at the beginning. How can this be? </li></ul></ul>
  4. 4. Quick Update <ul><li>Test from Tuesday </li></ul><ul><ul><li>If you haven’t taken it… </li></ul></ul><ul><ul><li>Grades finalized very soon (hopefully tomorrow) </li></ul></ul><ul><li>Progress reports to be printed just for science and signed </li></ul><ul><li>Extra Credit opportunities! </li></ul>
  5. 5. Share out
  6. 6. Law of Conservation of Energy <ul><li>Textbook pg 406-408 </li></ul><ul><li>Energy can not be created or destroyed. </li></ul><ul><li>Note: It’s a “law.” That means it’s always true. </li></ul>
  7. 7. Where’d it go? <ul><li>Mini-experiment: </li></ul><ul><ul><li>Change some chemical energy in your body into mechanical energy to rub your hands together </li></ul></ul><ul><ul><li>What do you notice is happening? </li></ul></ul><ul><ul><li>Explain what is happening scientifically. </li></ul></ul>
  8. 8. Where’d it go? <ul><li>Machines are supposed to help people make their jobs easier. But the work that a machine does is always less than the work that you must put into it at the beginning. How can this be? </li></ul><ul><li>Answer: Energy is always lost in the form of heat due to friction </li></ul>
  9. 9. <ul><li>http://www.lhup.edu/~DSIMANEK/museum/unwork.htm </li></ul>

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