From the figure (sorry for "paint" quality XD). A mass
is placed on a frictionless surface with angle
to the vertical line. It's pulled by constant force
using a massless string such that the mass don't float when it's pulled. After I stop pulling this mass when the rope does the angle
to the vertical line, find the amount of work done by
in
at the point when I stop pulling it.
Details:
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The work done is F* the parallel component of the displacement. The parallel component of the displacement can be found by finding the change in the length of the string from theta 1 to theta 2, because that's how much string the force F pulls. Thus delta x = sqrt(12^2+9^2) - sqrt(12^2+5^2) = 2m. Work = 2*42.25 = 84.5 Joules