Question

Which object has the higher temperature after being left outside for an entire winter night: a metal door knob or a rug? a) The metal door knob has the higher temperature. b) The rug has the higher temperature. c) Both have the same temperature. d) It depends on the outside temperature.

Short answer

Answer: c) Both have the same temperature.

Step-by-step solution

Understand the heat transfer processes

First, let's review the heat transfer processes involved. Two main processes are relevant for this exercise: conduction and convection. Conduction is the transfer of heat through a material, while convection is the transfer of heat via a fluid. In this case, the fluid is the air outside.

Analyze the thermal properties of the metal door knob and the rug

In general, metals have high thermal conductivity, meaning they can transfer heat quickly. Rugs, on the other hand, are made of materials with low thermal conductivity, acting as insulators. This means that the rug will lose heat at a slower rate compared to the metal door knob, given the same initial temperature.

Relate thermal properties to the heat transfer processes

Due to the higher thermal conductivity of the metal door knob, it would lose heat much faster through conduction compared to the rug. Furthermore, both the metal door knob and rug would lose heat through convection, but the rug's insulating properties may help slow down this process as well.

Determine the final temperature of both objects

Throughout the night, both objects would lose heat due to conduction and convection. However, since the metal door knob has a higher thermal conductivity, it would lose heat at a faster rate. Meanwhile, the rug would lose heat at a slower rate, due to its insulating properties. After an entire winter night, both objects would reach thermal equilibrium with the outside air.

Choose the correct answer

As both objects reach thermal equilibrium with the outside air, their final temperatures would be the same, despite the differences in heat transfer rates. Therefore, the correct answer is: c) Both have the same temperature.