well we could assume the air starts with zero velocity above the fan and hence zero momentum above the fan. We then calculate the velocity it has below the fan and hence the change in momentum. from the velocity we have calculated we can calculate the change in time?
Homework Statement
You are part of a team which hopes to build the worlds first 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 apporximated as a column of radius equal that of...