Question

Jane, whose mass is 50kg, needs to swing across a river(having width d) filled with man eating crocodiles to save Tarzanfrom danger. However, she must swing into a wind exerting withconstant
horizontal force F on a vine having length L and initially makingan angle ? with the vertical. Taking d=50m, F=110N, L=40m, and?=50degrees.
a) With what minimum speed must Jane begin to swing to just make itto the other side?
b) Once the rescue is complete, Tarzan and Jane must swing backacross the river. With what minimum speed must they begin theirswing? Assume Tarzan has a mass of 80kg.
Answer:

Part a)

D = Lsin + Lsinf, 50=40(sin50+sinf), f = 28.9 degrees

Ki + Ui + Wwind = Kf + Uf

1/2mvi2 + mg(-Lcos) + FD(-1)=0+mg(-Lcosf)

1/2(50)(vi)2 + 50(9.8)(-40cos50)-110(50) =50(9.8)(-40cos28.9)

vi = 6.15 m/s

Part b)

1/2mvi2 + mg(-Lcosf) + FD(+1) = 0+mg(-Lcos)

1/2(130)(vi)2 + 130(9.8)(-40cos28.9)+110(50) =130(9.8)(-40cos50)

vi = 9.87 m/s

I know the answer, but i just need to do it in A B C D method.step a, list the givens and unknowns. step b, write down formulasthat you will use. step c, change up the formula to find theunknowns or the information that you need to figure out. step d,plug in the numbers or in other words the givens to solve theproblem.

I need both parts A and B to be in the A B C Dmethod.