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rhotonsix
- 6
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My understanding of static friction is that it is a resistive force in response to an applied force. I recently read the following example. A rope of uniform density, length L, is fastened to a plane with incline angle “theta” along its length. The question asks for the tension at the top of the rope where it is fastened to the plane. The solution states that the direction of the static friction depends on how the rope arrived on the plane - if it is simply placed on the plane and fastened the static friction points up the plane, while if the rope was dragged up the plane and fastened, the static friction force points down the plane. This in turn will affect the tension. I get why if one drags the rope up the plane there is a resistive kinetic friction force in the opposite direction. But it seems to me that once the rope is fastened on the plane and is at rest, the forces it experiences are the same regardless of how it got there and hence the static friction would be the same. Where am I wrong? Thanks in advance.