1. The problem statement, all variables and given/known data Air is flowing with a speed v in the direction (-1, -1, 1,) calculate the volume of air flowing through the loop consisting of straight lines joining (in order i presume) (1,1,0) (1,0,0) (0,0,0) (0,1,1) (1,1,0) 2. Relevant equations 3. The attempt at a solution I assume you have to do a surface integral to calculate the area of the loop, calculate the component of air that is flowing in that direction and do a simple velocity * area for volume per second? Not sure how to get started with the first two parts though.