Challenge date 09-03-2026

See the figure. A box weighing 50 N rests on a horizontal floor. A weightless round drum is welded to the box. Do a planar analysis (no out of plane motions). A massless inextensible string attached to an immovable fixed point above passes around the drum as shown. The rising part of the string makes an angle θ = 13◦ with the vertical, as shown. The friction coefficient between the box and the ground is 0.05, and that between the string and drum is 0.05 as well. Find the horizontal force T needed on the string to cause the box to slide slowly. The box is long enough that it slides: it does not pivot about an endpoint. Note that the upper part of the string has a tension that may be higher or lower than T. (Which is it?)

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