$1$ A thin plate is moving in a direction parallel to its length in still air at a velocity of $4\mathrm{.}0\frac{m}{s}.$ The length of the plate is $0\mathrm{.}5$ m and width is $0\mathrm{.}6$ m $.$ Taking $v_{\text{a}\text{i}\text{r}}=1\mathrm{.}5{10}^{-5}\frac{m^2}{s}$ and ${}_{\text{a}\text{i}\text{r}}=1\mathrm{.}25k\frac{g}{m^3},$ calculate $($a$)$ the boundary layer thickness at the end of the plate, $($b$)$ shear stress at $20$ cm from the leading edge, and $($c$)$ drag force on one side of the plate. $.$ Ans. $($:$=6\mathrm{.}847(mm),{}_0=0\mathrm{.}02875(Pa),F_D=0\mathrm{.}0109(N)$