Homework Help: Air conditioning

1. Dec 6, 2004

SnowOwl18

----A room has a volume of 121m^3. An air-conditioning system is to replace the air in this room every thirty minutes, using ducts that have a square cross section. Assuming that air can be treated as an incompressible fluid, find the length of a side of the square if the air speed within the ducts is 2.86m/s.----

Um...I'm lost on this one. Not sure where to start...any help would be much appreciated. :)

2. Dec 6, 2004

dextercioby

First of all,u need to transform the time given (30 mins) into seconds.The result is,obviously,1800 secs.Since all the air in is evacuated within this time,calculate the flow (how many cubic meters of air is taken out in one second).Once u got the flow,the area is simple to determine,since the flow is intimately linked with the speed and the surface.Actually it's the product of the 2.You have the flow,the speed,so the area is easy to calculate.

Good luck!!

Daniel.

3. Dec 6, 2004

SnowOwl18

oo thank you so much! you rock :D

4. Dec 6, 2004

dextercioby

You're welcome!!