Solve this.To compare the thermal behavior between Copper and AISI $4340$ steel, you analyze the heat flow in semi$-$infinite solids that are made

from these two materials. These semi$-$infinite solids are initially at $20C,$ and at time $t=0,$ the surface temperature at $x=0$ is instantly

increased to $100C.$

For copper, $=8930\frac{kg}{m^3},C=385\frac{J}{kgK},=398\frac{W}{mK}$

For AISI $4340$ steel, $=7850\frac{kg}{m^3},C=475\frac{J}{kgK},=44\mathrm{.}5\frac{W}{mK}$

a$)$ For each material find the temperature, in $C,$ at $x=13\mathrm{.}5mm$ at time $t=9sec.($enter the value with at least three significant digits$)$

Copper:

AISI $340$ steel:

b$)$ In Part a$,$ why is the temperature of copper higher than that of AISI $4340$ steel?

Because copper has a higher thermal conductivity than the steel.

Because copper has a higher density than the steel.

Because copper has a higher specific heat than the steel.

Because copper has a higher thermal diffusivity than the steel.