1. The problem statement, all variables and given/known data For decades, people have dreamed of cars that can ﬂy. You are part of a team which hopes to build the worldʼs ﬁrst commercial ﬂying car. Your proposed design has four fans, each of radius 50cm. Each fan sucks in air from above the car and blows it downwards. The downward ﬂow of air can be approximated as a column of radius equal to that of the fan, traveling at a uniform speed downwards. How fast must the air be blown downwards if the car plus passengers weigh 1000 kg? You may assume that the density of air is 1.2 kg m-3. 2. Relevant equations 3. The attempt at a solution I have considered pressure differences, and conservation of angular momentum, but I cant seem to apply them in any way that helps me solve for the required unknown.