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Work

  • The idea of work is deeply connected to the idea of energy, as we will see in coming lessons.
  • Qualitatively, you've done more work on an object if you push with more force than less force. Similarly, you do more work if you push for a longer distance than less distance.
  • We want to define work as how much change you put into the world. Even if an object moves a distance, your force has to have some effect on the object's motion. No effect, no work.
  • This means that if your force is perpendicular to the movement, it contributes nothing-no work.
  • Work is the distance traveled multiplied by the force parallel to the motion. If the angle between them is θ, we can use trigonometry to get
    W = |

    F
     
    | ·|

    d
     
    | ·cosθ.
  • The unit for work is the newton·meter, which we call a joule (J).

Work

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Physics (Theory and Application)