A one-fourth scale model of a car is to be tested in a wind tunnel. The conditions of the actual car are V = 45 km/h and T = 0°C and the air temperature in the wind tunnel is 20°C. In order to achieve similarity between the model and the prototype, the wind tunnel is run at 204 km/h.

The properties of air at 1 atm and 0°C: ρ = 1.292 kg/m³, ν = 1.338 × 10^–5 m²/s.

The properties of air at 1 atm and 20°C: ρ = 1.204 kg/m³, ν = 1.516 × 10^–5 m²/s.

If the average drag force on the model is measured to be 70 N, the drag force on the prototype is

(a) 17.5 N 

(b) 58.5 N 

(c) 70 N 

(d) 93.2 N 

(e) 280 N