During a spring evening

PHYSICS · Subjective · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

During a spring evening, the outdoor air temperature falls linearly from 10 ∘ ⁣C10\,^{\circ}\!\text{C} at 18:00 to −2 ∘ ⁣C-2\,^{\circ}\!\text{C} at 00:00. Inside a house, the temperature is held at 22 ∘ ⁣C22\,^{\circ}\!\text{C}. The house has a single-pane glass door of area 2.5 m22.5\,\text{m}^2 and thickness 8.0 mm8.0\,\text{mm} with thermal conductivity 0.80 W m−1K−10.80\,\text{W\,m}^{-1}\text{K}^{-1}. Estimate the total thermal energy, in megajoules, that passes through the door during this 6 h interval by using the average temperature difference.

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