Question

A fan causes a velocity field that falls off
inversely with the distance from the fan. For
one fan, the air speed at 1.3 m is 6.3 m/s. If
two of these fans are placed 3 m apart, pointed
at each other, what will be the air speed 1 m
away from one of the fans?

Answer 1

v = k/r^2
solve for k
Now use k and find v for r=1 and r=2.
The difference of those (remember v is a vector) will be your answer.