2014: Problem 19

Topic: Dynamics
Concepts: Air resistance, Newton’s laws

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Solution:

Every small piece of cable feels the same friction force $\vec{f}$ to the left and the same weight $\vec{w}$ downward since they both depend only on the length of the piece. Thus, all the pieces of rope effectively have weight $\vec{w}’=\vec{w}+\vec{f}$ towards the bottom left direction. We know a massive rope hangs downwards in the direction of its weight so the answer is B.

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