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Comment by cynicalkane | Hacker News Reader

Well, the diagram is impossible unless the weights are all resting on the floor, so let's assume they are. This system will find a steady state only at a local minimum of potential energy, so the lightest weight will be lifted before the heavier two get off the ground.

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Assumptions:

  pulleys: idealized, massless, frictionless

  rope: idealized, massless, doesn't stretch

  weights: resting on ground.

As tension is applied to the rope, Weight A will be lifted first, until it is lifted to the ceiling. Then Weight B, and finally Weight A.

It helps to visualize Weight A as being massless. In that case, there would just be extra slack in the rope, and B&C would not move until the slack was taken in.

* Then Weight B, and finally Weight A.*

I believe you meant C, correct?

Yes, I meant C. Too late to go and fix it now. Good catch

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huh.. i didn't think of them resting on the ground and thought it was a trick question.

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