Question $1$

$3$ pts

A small brick has a thermal conductivity of $0\mathrm{.}69\frac{W}{mK}.$ The brick is at $30C$ when it is placed in a freezer with air at $0C.$ The walls, ceiling and floor of the freezer are kept at $-10C.$ The brick has a heat transfer coefficient of $10\frac{W}{m^2(K)}.$ The correct equation to find the emissivity of the brick is:

$Q^{}=m^{}{c}_{p}T$

$Q^{}=-kA\frac{dT}{dx}$

$Q^{}=h{A}_S(T_s-T_{})$

$Q^{}=lon{A}_s(T_s^4-T_{\text{s}\text{u}\text{r}\text{f}}^4)$