A rock with mass m = 3.00 kg is suspended from the roof of an elevator by a light cord. The rock is totally immersed in a bucket of water that sits on the floor of the elevator, but the rock doesn't touch the bottom or sides of the bucket
(a) When the elevator is at rest, the tension in the cord is 21.0 N. Calculate the volume of the rock.
(b) Derive an expression for the tension in the cord when the elevator is accelerating upward with an acceleration of magnitude a. Calculate the tension when a = 2.50 m/s2 upward.
(c) Derive an expression for the tension in the cord when the elevator is accelerating downward with an acceleration of magnitude a. Calculate the tension when a = 2.50 m/g' downward.
(d) What is the tension when the elevator is in free fall with a downward acceleration equal to g?