Q$1.(35$ pints$)$ A long, hexagonal copper extrusion is removed from a heat$-$treatment oven at $400C$ and immersed in a $50C$ airstream flowing perpendicular to its axis at $10\frac{m}{s}.$ The rod is $3$ cm across opposing flat sides and has a cross$-$sectional area of $7\mathrm{.}79c{m}^2$ and a perimeter of $10\mathrm{.}4$ cm $.$ Determine the time required for the center of the copper to cool to $100C.$ Is your answer accurate?