Question

I am pretty confused about the reasoning behind the equations for challenge problem number 1 of the Problem Solving module. Link: http://ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/problem-solving-and-estimation/MIT8_01SC_problems02_soln.pdf

Answer 1

This is not in any way an answer, but just a path. How much force does the ice mantle put on to the liquid region? I would like to know the force exerted by the mantle, which would be the mass of a hollow sphere bounded by 8 km thick walls. I have to assume that the liquid ocean is "at rest" so I can apply Pascal's pressure law to the liquid which would add the force of the entire ice mass to the pressure exerted by a single column of liquid water.

Answer 2

Oh okay, I did not think to consider the qualifications for the application of Pascal's rule. It was hard for me to interpret what each of the components of equations 1.1 and 1.4.

Answer 3

The force if given by mgh where m = density times volume and volume = area times height
volune = Area times height. The area in the pressure expression will cancel with the ares in the volume expression