The train travels at 30 m/s and consists of an engine and a series of cars.Determine the approximate thickness of the boundary layer and the shear stress acting on the

top of a car at x = 18m from the front of the train.The air is still and has a temperature of 20°C. Assume he surface are smooth and flat, and the boundary layer is completely turbulent.You must use the momentum equation to derive the ions.

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