Nectar is being processed in the factory of heaven. The nectar is rotating inside a gold cylinder with an angular velocity of $\omega =4 \space rad/sec$ If nectar is a fluid and its surface can be expressed as a function of $x$ and $y$, where $f(x, y)=z$, $x=2\space m$, and $y=1\space m$, what is the value of $z$?

Assume, $g=10\space m/s^2$.