$(15$ points$)$ A square chip with a side length of $L=35mm$ is insulated on one side and cooled on the other side by an air stream at a velocity of $v_{}=30\frac{m}{s}$ and a temperature of $T_{}=25C,$ mounted in a plate providing an unheated starting length of $5$ mm $($Figure $2).$ The chip maintains a constant surface temperature $T_s=90C$ at the cooled side. The air stream has the kinematic viscosity $v=20{10}^{-6}\frac{m^2}{s},$ the thermal conductivity of $k=0\mathrm{.}03\frac{W}{m}*K,$ and Prandtl number $Pr=0\mathrm{.}70.$ What is the rate of convective heat loss from the chip?

$air{T}_{}$

Figure $2$