# The velocity profile of an incompressible laminar boundary layer over a flat plate developing under constant pressure is given by $\frac{u(y)}{U_{\infty}}=\frac{3 y}{2 \delta}-\frac{1}{2}\left(\frac{y}{\delta}\right)^{3}$. The freestream velocity $U_{\infty}=10 \mathrm{~m} / \mathrm{s}$ and the dynamic viscosity of the fluid $\mu=1.8 \times 10^{-5} \frac{\mathrm{kg}}{\mathrm{ms}}$. At a streamwise station where the boundary layer thickness $\delta=5 \mathrm{~mm}$, the wall shear stress is ___________$\times 10^{-3} P a$

## Question ID - 155730 :- The velocity profile of an incompressible laminar boundary layer over a flat plate developing under constant pressure is given by $\frac{u(y)}{U_{\infty}}=\frac{3 y}{2 \delta}-\frac{1}{2}\left(\frac{y}{\delta}\right)^{3}$. The freestream velocity $U_{\infty}=10 \mathrm{~m} / \mathrm{s}$ and the dynamic viscosity of the fluid $\mu=1.8 \times 10^{-5} \frac{\mathrm{kg}}{\mathrm{ms}}$. At a streamwise station where the boundary layer thickness $\delta=5 \mathrm{~mm}$, the wall shear stress is ___________$\times 10^{-3} P a$

3537

Answer Key : (53.9 to 54.1) -

53.9 to 54.1

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The Pitot tube of an aircraft registers a pressure $p_{0}=54051 \mathrm{~N} / \mathrm{m}^{2} .$ The static pressure, density and the ratio of specific heats of the freestream are $p_{\infty}=45565 \mathrm{~N} / \mathrm{m}^{2}, \rho_{\infty}=0.6417 \mathrm{~kg} / \mathrm{m}^{3}$ and $\gamma=1.4,$ respectively. The indicated airspeed $(\mathrm{in} m / s)$ is
(A) 157.6
(B) 162.6
(C) 172.0
(D) 182.3 