A single blanket 4 cm thick has K = 0.04 W m − 1 K − 1 . Two blankets of 2 cm each with a 2 mm air gap ( K ai r = 0.024 ) are used in its place. Find the ratio of the heat flow per unit area through

Question

A single blanket 4 cm thick has K = 0.04 W m − 1 K − 1 . Two blankets of 2 cm each with a 2 mm air gap ( K ai r ​ = 0.024 ) are used in its place. Find the ratio of the heat flow per unit area through the single blanket to that through the two-blanket arrangement for the same temperature difference (two decimals).

TestHub · Accepted Answer

Thermal resistance per unit area: single 0.04 0.04 ​ = 1.000 . Two blankets: 2 × 0.04 0.02 ​ + 0.024 0.002 ​ = 1.083 . The flow is inversely proportional to the resistance, so the ratio = 0.92 .

Physics - Heat & Thermo Question with Solution | TestHub

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