Generalization of WE equation to cover rotation

# Generalization of WE equation to cover rotation -...

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Generalization of WE equation to cover rotation So our WE equation remains, But now we include the fact that work can be done by torques according to the equation above, and that if an object is rotating, it has an additional KE of: Example If the disk is rotating at a rate of 3 rad/s. What F must be applied to slow it down to rest in 5 rev.? We apply the WE equation. The work done on the disk is that done by the torque supplied by F. The energy of the disk is purely rotational kinetic energy. Example: Pushing open a door Suppose you’re trying to push open a door of mass 50kg, width 1m, and height 2.5m. If the hinges exert a counter torque of τ hinge = -100N·m z . If you apply a force of 220 N, how fast will the door be rotating by the time you’ve pushed it through an angle of 30 degrees? The situation is illustrated, top-down, below: We can apply the WE equation to the door. Since the hinge force and F-force are non-conservative, and since the change in energy of the door is purely kinetic, we have, So,

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• Spring '13
• DanielSantavicca

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