Question

Module 2,Challenge problem 1 :Fermi Problem : I dont understand the solution at all.Will somebody plz elaborate the solution sply the equation part, what is z, how the calculation is done here .Thnks.

Answer 1

z is the depth, so z = 0 is the surface of the sea. \[\Delta Z\] is a slice of the column of water.
The equation (1.1) is the force acting on \[\Delta Z\] (that's a typo). this is equal to 0 because the slice neither rises nor falls.
That's the beginning, if you need more help ...