Calculate variation in volume using given Poisson's ratio

[abhishek4]

Homework Statement

: A cylinder is elongated by 2% of its original length. If Poisson's ratio of its material is 0.3. Calculate the percentage variation in volume.[/B]

Homework Equations

V = πr^2l
η= 0.3= Δl/l/Δr/r[/B]

The Attempt at a Solution

I tried using calculus to differentiate V to find change in volume and then divided it by the given volume but could not find and answer as r^2 was left.

 

[haruspex]

I think you have the definition of Poisson's ratio wrong. It should be the other way up and negated: $-\frac{\Delta r/r}{\Delta l/l}$.
Please post your working.