Proving coefficient of volume expansion

[bray d]

Homework Statement

Prove the equation B=3A, where B is the coefficient of volume expansion and A is the coefficient of linear expansion, considering a cube of side 's' and therefore volume V=s^3 that undergoes a small temperature change 'dT' and corresponding length and volume changes 'ds' and 'dV'.

Homework Equations

B=(deltaV/V)/deltaT
A=(deltaL/L)/deltaT

The Attempt at a Solution

I think I need to prove the coefficient of linear expansion, then prove the coefficient of volume expansion and observe the relationship between the two. I don't know where to start though, or if there is a more straight forward way. any help is appreciated, thanks

 

[bray d]

I was thinking of using the ideal gas law:
PV=nRT

but ITS NOT A GAS. I'm lost

 

[Saladsamurai]

Are you sure that you don't just need to show that if the coefficient of linear expansion is A then the coefficient of volume of expansion is just 3A?

I feel that this is more likely the question being asked.