A granite wall has a thickness of 0.50 m and a thermal conductivity of 2.1 W/(m·C°).The temperature on one face of the wall is 5.2 °C and 20.0 °C on the opposite face.How much heat is transferred in one hour through each square meter of the granite wall?

Question

Quizplus · Accepted Answer

First, we need to calculate the temperature difference across the wall:

ΔT = 20.0°C - 5.2°C = 14.8°C

Next, we can use the formula for heat transfer through a plane wall:

Q = kAΔT/dt

where Q is the heat transfer rate, k is the thermal conductivity, A is the area, ΔT is the temperature difference, d is the thickness, and t is the time.

We can simplify this to:

Q = kAΔT/d

We are asked for the heat transferred per square meter of wall, so we can set A = 1m².

Plugging in the values:

Q = (2.1 W/(m·°C))(1 m²)(14.8°C)/(0.50 m)(3600 s)

Q = 2.2 × 10⁵ J/m²

Therefore, the correct answer is A.

A Granite Wall Has a Thickness of 0