You do 174 J of work while pulling your sister back on a 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)22.9 kg
B)19.5 kg
C)26.3 kg
D)28.4 kg

Question

Quizplus · Accepted Answer

The work done is equal to the change in potential energy of the system. The change in potential energy is equal to the mass of the system 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 system 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. Plugging in the given values, we get:$$m = \frac{W}{gL\sin	heta} = \frac{174 J}{(9.8 m/s^2)(5.10 m)\sin32.0^\circ} = 22.9 kg$$

You Do 174 J of Work While Pulling Your Sister