Physics

Physics

Problem

A solid cylindrical copper rod of length 0.25 m0.25\,\text{m} is meant to conduct 1.0×103 W1.0\times10^{3}\,\text{W} of thermal energy from an engine block at 200 ∘C200\,^{\circ}\text{C} to a coolant reservoir at 50 ∘C50\,^{\circ}\text{C}. Spatial constraints limit the rod’s diameter to no more than 1.5 cm1.5\,\text{cm}. Copper has thermal conductivity 400 W ⁣/ ⁣(m⋅ ⁣∘C)400\,\text{W}\!/\!(\text{m}\cdot\!^{\circ}\text{C}). Which statement correctly describes whether the design goal is achievable and, if not, what diameter would be required? a) No; the rod would need a diameter of roughly 3.6 cm3.6\,\text{cm} to conduct the required power. b) Yes; the goal is achievable with the maximum allowed diameter of 1.5 cm1.5\,\text{cm}. c) No; the rod would need a diameter of roughly 7.3 cm7.3\,\text{cm} to conduct the required power. d) No; the rod would need a diameter of roughly 14.6 cm14.6\,\text{cm} to conduct the required power.

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