If the height of the parapet is 200. ft, and the weight of the person is 150. lbf, and the unstretched length L = 45.0 ft, find a value of K that enables this person to stop exactly five feet above the ground. (A: 2.60 lbf/ft)

At full stretch, the elastic rope of original length L stretches to L + x. For a person whose weight is W lbf and a cord with a stiffness K lbf/ft, the extension x is given by this formula:

 

and that can be written in spreadsheet script as x = W/K + sqrt(W^2/K^2 + 2 * W * L/K).

Transcribed Image Text:

w2 2W x L W X=ー+ K*VK K