400
When water is drained out of a conical tank, the volume V, the radius r, and the height h of the water level are all functions of time t. Knowing that theses variables are related by the equation:
∏
V = ---- r^2h
3
At what rate is the volume changing?
dV ∏
----- = ----- (r^2(dh/dt) + 2rh(dr/dt))
dt 3