Water is heated in an open pan at air pressure 10⁵ Pa. It remains liquid and expands slightly as it is heated. Find the ratio of heat absorbed by the water to the work done by the water. For water, γ=10⁻³ °C⁻¹ and S=1 cal g⁻¹ °C⁻¹.
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Question

Water is heated in an open pan at air pressure 10⁵ Pa. It remains liquid and expands slightly as it is heated. Find the ratio of heat absorbed by the water to the work done by the water. For water, γ=10⁻³ °C⁻¹ and S=1 cal g⁻¹ °C⁻¹.

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G1 Physics · Accepted Answer

Use the first law Q=ΔU+W (W by the gas), ΔU=nCᵥΔT for an ideal gas, and the appropriate process relation. For Carnot devices, let T₁ be the cold-reservoir temperature and T₂ be the hot-reservoir temperature; η=1−T₁/T₂ and COP=T₁/(T₂−T₁). Evaluating the given data/statements gives D: 4.2 ×10⁴. Therefore the correct answer is D.