A brass rod with a length of 20.0 cm is placed end to end with an aluminum rod with a length of 20.0 cm, and this system is placed between a hot temperature of 100 °C and a cold temperature of 10.0 °C. The thermal conductivities of the brass and the aluminum are 100 W/m °C and 230 W/m °C, respectively. The rods have the same cross-sectional area of 25.0 cm². What is the heat flow from the hot temperature to the cold temperature?

Question

Quizplus · Accepted Answer

The heat flow through each rod can be calculated using the formula $ Q = \frac{k \cdot A \cdot \Delta T}{L} $. For the brass rod, $ Q_{brass} = \frac{100 \cdot 0.0025 \cdot 90}{0.2} = 112.5 $ W. For the aluminum rod, $ Q_{aluminum} = \frac{230 \cdot 0.0025 \cdot 90}{0.2} = 258.75 $ W. Since they are in series, the total heat flow is determined by the rod with the lower heat flow, which is the brass rod. Therefore, the heat flow is approximately 78.4 W.

A Brass Rod with a Length of 20