Direction: A smooth flat plate with a sharp leading edge is placed along a gas stream flowing at U = 10 m/s. The thickness of the boundary layer at section r – s is 10 mm, the breadth of the plate is 1 m (into the paper) and the density of the gas, ρ = 1.0 kg/m3. Assume that the boundary layer is thin, two-dimensional, and follows a linear velocity distribution, u = U (y/δ), at the section r–s, where y is the height from plate. 
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The integrated drag force (in N) on the plate, between p – s, is
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- 0.67
- 0.33
- 0.17
- zero
Correct Option: C
By momentum equation, we can find drag force.
