Center of Mass on Moving Plank · PhysicsBowl 2017 #34
Physics · mechanics
Problem
A 9.20 m long uniform plank rests on a frictionless ice pond. A 52 kg box rests on the plank's left end while a 71 kg person stands at the plank's right end. After the person walks to the left on the plank and stands at the same location as the box, the plank has slid 3.84 m to the right relative to the pond's shore. Which one of the following choices best represents the mass of the plank?
[Figure: Diagram showing plank with box and person before and after movement]
(A) 123 kg (B) 61.5 kg (C) 47.1 kg (D) 36.5 kg (E) 31.2 kg