You do 116 J of work while pulling your sister back on a fritctionless swing, whose chain is 5.10 m 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) 19.0 kg
D) 17.6 kg

Question

Quizplus · Accepted Answer

The correct answer is A because the work done is equal to the change in potential energy of the swing, which is equal to the mass of the swing times the acceleration due to gravity times the change in height. The change in height is equal to the length of the chain times the sine of the angle, so the mass of the swing is equal to the work done divided by the acceleration due to gravity times the length of the chain times the sine of the angle.

You Do 116 J of Work While Pulling Your Sister