Consider the extrusion of a cylindrical billet. assume the starting billet to have a length of 0.3 m and a diameter of 15 cm. this is extruded into a cylindrical product that is 3 cm in diameter and 7.5 m long (a reduction ratio of 25). neglecting the areas on the two ends, compute the ratio between the product surface area (wrap around cylinder) and the surface area of the starting billet. (2 points)

1in2 processor chip can be modelled as an isothermal plane wall of silicon, isothermal on both sides. the power input to the bottom of the plane wall, or the processing power of the chip, often called the thermal design power (tdp), is 100w. assume the periphery is adiabatic. the silicon is 400 microns thick. the temperature at the junction, or in this case on the bottom of the isothermal plane wall, is 85°c. what is the top surface temperature, assuming that the only mode of heat transfer is conduction