$+-$ Kvers

The In flow over a surface, velocity, and temperature profiles are of

$u(y)=r{y}^4+F{y}^3+G{y}^2+Hy$

$T(y)=A{y}^4+B{y}^3+C{y}^2+Dy+I$

Where the coefficients A through $11$ are constants. Obtain expressions for the friction cosflicient $C_f$ and the convection coefficient $h$ in terms of $u_m,T_m,$ and appropriate profle coefticients and fluid properties.

$(11$ Peints$)$ Question Three: Steel balls $12$ mm in diameter are annealed by heating to $1250$ K and then slowly cooling to $400$ K in an air environment for which $T_{}=300K$ and $h-30W^2{m}^{2}K.$ Assuming the properties of the steel to be $k=40\frac{W}{m}.$ K$,=7800k\frac{g}{m^3},$ and $C_P=600\frac{J}{k}g.K,$ estimate the time required for the cooling process.

Steel $,T_i=1250K$

$k=40\frac{W}{m}*K$

$=7800\frac{k}{m^3}$

$c=600\frac{J}{k}g*K$