Tiltmeter problem

1. The problem statement, all variables and given/known data
Geologists place tiltmeters on the sides of volcanoes to measure the displacement of the surface as magma moves inside the volcano. Traditional tiltmeters consist of two or more water filled metal cans placed some distance apart and connected by a hose. Suppose two can are placed so that the water level in both is initially at the 5 cm mark. A week later, the water level in can 2 is at the 6.5 cm mark. The cans are 100 m apart.

a) Did can 2 move up or down relative to can 1? By what distance?

b) Where is the water level now in can 1?


2. Relevant equations



3. The attempt at a solution

For part a, here is what I thought, but I'm not sure that it's right:

Since the water in can 2 rises, the pressure increases. I think that the pressure in both of the cans has to be the same. Since can 1 now has a lower water level, it must be at a lower level than can 2. Does can 2 move up by 1.5 cm?

 

Ok, I tried that, but I don't think I understand the underlying concept. Is this a pressure problem?