Question

A person is losing thermal energy through the skin at a rate of 120 W when his skin temperature is 30°C. He puts on a sweater, and his skin temperature rises to 33°C. The effective thermal conductivity between his core and the environment changes from 0.22 W/m·K to 0.18 W/m·K. At what rate (J/s) is he now losing thermal energy?

Answer 1

To calculate the rate of heat conduction out of the human body, use the formula Q = k * A * (ΔT / d), where Q is the rate of heat transfer, k is the thermal conductivity, A is the surface area, ΔT is the temperature difference, and d is the thickness of the tissue between the core and the skin.

Step-by-step explanation:

To calculate the rate of heat conduction out of the human body, we can use the formula Q = k * A * (ΔT / d), where Q is the rate of heat transfer, k is the thermal conductivity, A is the surface area, ΔT is the temperature difference, and d is the thickness of the tissue between the core and the skin.

In this case, the initial thermal conductivity is 0.22 W/m·K, the final thermal conductivity is 0.18 W/m·K, the initial skin temperature is 30°C, and the final skin temperature is 33°C. The thickness of the tissue is not provided, so we cannot calculate the exact rate of heat transfer without this information.

However, we know that the rate of heat transfer is directly proportional to the thermal conductivity and the temperature difference, and inversely proportional to the thickness of the tissue. Therefore, if the thermal conductivity decreases and the temperature difference increases, the rate of heat transfer will increase.