The flow rate of a liquid through a 3.0-cm-radius pipe is 3.0 x 10-3 m3/s. What is the average fluid speed in the pipe?
v * area = volume/second
area = pi r^2 = pi (3/100)^2 = 9 pi /10^4 m^2
v = 3 * 10^-3 m^3/s / (9 pi *10*-4 m^2) = 30/ (9 pi) = 1.06 m/s