A rock of mass M, that has a density equal to 150% that of water, is suspended in water by a thin, massless cord. The tension in the cord is
A) 2Mg.
B) Mg.
C) 4Mg.
D) zero.
E) 3Mg.

Question

Quizplus · Accepted Answer

The tension in the cord is equal to the weight of the rock minus the buoyant force. Since the rock's density is 150% that of water, the buoyant force is 2/3 of the rock's weight, making the tension 1/3 of the rock's weight, which is Mg.

A Rock of Mass M, That Has a Density Equal