A rectangular duct with air flowing measures 1 foot by 3 foot so that it can fit in a ceiling crawl space and it is to be compared to a 2 foot

A rectangular duct with air flowing measures 1 foot by 3 foot so that it can fit in a ceiling crawl space and it is to be compared to a 2 foot diameter round duct, which has a similar mass flow of air for the same velocity. Use the round duct as the base case. Note that the hydraulic diameter is equal to 4 times cross sectional area divided by the wetted perimeter (verify this relationship by finding the hydraulic diameter of the round duct which should be equal to diameter