Jane, whose mass is 51.5 kg, needs to swing across a river (having width D) filled with person-eating crocodiles to save Tarzan from danger.

She must swing into a wind exerting constant horizontal force F, on a vine having length L and initially making an angle ? with the vertical (see below figure). Take D = 51.0 m,F = 107 N,L = 40.0 m, and ? = 45.0°