Chapter 4,5 and 6 crossword

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Across
  1. 3. reducing friction can ____ efficiency
  2. 4. an inclined plane
  3. 5. Force * displacement
  4. 6. useful work/total work
  5. 9. output force/input force
  6. 12. a machine cant _____ the magnitude of work
Down
  1. 1. in order to perform a task the ____ of a system interact
  2. 2. a force that opposes motion
  3. 5. device that converts sliding friction to rolling friction
  4. 7. lever with load in the middle
  5. 8. uses mechanical advantage to change torque
  6. 10. sometimes wasted energy in systems is released as ____
  7. 11. any device that transmits force to do work