On a cruise ship, passengers complain about the noise emanating from the ship's propellers (probably due to turbulent flow effects between the propeller and the ship). You have been hired to find out the source of this noise. You will study the flow pattern around the propellers and have decided to use a 1:9-scale water tank. If the ship's propellers rotate at \(100 \mathrm{rpm}\), estimate the model propeller rotation speed if

(a) The Froude number 

(b) The Reynolds number is the governing dimensionless group. Which is most likely to lead to the best modeling?