Question

29) You do 116 J of work while pulling your sister back on a fritctionless swing, whose chain is  long, until the swing makes an angle of 32.0° with the vertical. What is your sister's mass?

A) 15.3 kg

B) 13.0 kg

C) 17.6 kg

D) 19.0 kg

Answer 1

Length of the chain l = 5.10 m ( Suppose)

angle made with verticle θ = 32 degrees

Potentential energy gained = 116 J

               mgl(1 - cosθ) = 116

             m*9.8*5.1(1 - cos32) = 116

                 m * 49.98 * 0.1519 = 116

                              7.594 m = 116

                             mass m = 15.27~15.3 Kg

Option A is correct Answer .

I hope help you.