Size of pipe needed to transport helium problem

[AlaskanPow]

Homework Statement

An engineer is designing a system that requires transporting .01 m^3/s of helium at 15°C and 120 kPa. The velocity of the pipe is limited to 40 m/s. What size (diameter) of pipe is needed?

My question is what equation do i need to solve this problem?

Homework Equations

Im not sure possibly Bernoulli's equation.

The Attempt at a Solution

need equation first

 

[SteamKing]

The problem is not asking you to find any pressure drops or changes in velocity of the helium. The problem is simply this: given the volumetric flow rate and the maximum speed of the helium, what is the diameter of the pipe required to satisfy these constraints? Hint: think continuity.