Pressure and Velocity Change When Merging two tubes

[Gerald Funk]

Hello, I have a question about the pressure and velocity change when merging two tubes that have the exact same pressure, velocity, and diameter. I've attached an image to give you guys a visualization. Say the three tubes are all laying flat on the ground, so there's no height change.

What I'm trying to figure out is what the velocity and the pressure of the third tube.
I calculate that the density of the first two tubes would be 103.4 kg/m^3, would this value double in the third tube? And how would this effect the velocity and pressure?
Any information helps

 

[gtoguy97]

!The velocity of the third tube should remain the same as the velocity of the first two tubes since there is no height change. The pressure of the third tube should also remain the same. However, the density will double because the volume of air in the third tube has doubled. This means that the mass of air in the third tube has also doubled, while the volume remains the same, so you would divide the mass by the volume to get a double density.