String constant and bouyant force question

[lonelypeoplez]

1. The problem statement, all variables and given/known data
a spring 15 cm long ,
a aluminum cylinder of 70grams, 1 cm radius is given.

attach cylinder to spring, the spring stretches to equilibrium of 16.1cm

2cm of cylinder is submerged into water, the length of stretched spring is 15.8cm
3cm of cylinder is submerged, length of spring is 15.7
4 15.6
5 15.5
6 15.4
7 15.3


2. Relevant equations
Fb = (mg) (fluid)
bouyant force = mass times G

Rho =m/v, so Fb = (pVg)
^
rho

Vcylinder = pie r*r (h)

Fs= kx

spring force = constant(stretched length? not sure)


3. The attempt at a solution

we are to come up with a equilibrium expression for the cylinder in water below a depth of x by inserting mass, volumn and force into the equations above


im realyl stuck here, i dont know exactly what a equilibrium expressions is asking for, please help