A one-third scale model of an airplane is to be tested in water. The airplane has a velocity of 900 km/h in air at –50°C. The water temperature in the test section is 10°C.

The properties of air at 1 atm and –50°C: ρ = 1.582 kg/m³, μ = 1.474 × 10^–5 kg/m·s.

The properties of water at 1 atm and 10°C: ρ = 999.7 kg/m³, μ = 1.307 × 10^–3 kg/m·s.

In order to achieve similarity between the model and the prototype, the water velocity on the model should be

(a) 97 km/h 

(b) 186 km/h 

(c) 263 km/h 

(d) 379 km/h

(e) 450 km/h