A spherical-shaped hollow steel shell, with a radius of 2.5m, containing some instruments, is lowered by a cable into a lake. The shell with its contents weighs 7.2 * 10^5 N on the deck of the ship from which it is being lowered. What is the tension in the cable when the sphere is completely immersed in water?
a. 1.8 kg
b. 2.9 * 10^4 N
c. 7.9 * 10^4 N
d. 7.2 * 10^2 N
The question is solved equationally.