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QPages 96-97: Q3: HC Verma: Concepts of Physics - Volume 2 Heat Transfer Pages 96-97: Q3 Solution: Why does blowing over a spoonful of hot tea cools it? Does…

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Students often attribute the cooling solely to forced convection from the breath and overlook that the dominant effect is evaporative cooling, which removes latent heat from the tea. Remember that blowing increases the vapor‑pressure gradient, accelerating evaporation, while radiation contributes only a minor amount for a small spoonful.

Why does blowing over a spoonful of hot tea cools it? Does evaporation play a role? Does radiation play a role?

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**Answer:** Blowing cools tea by increasing evaporation. Yes, evaporation plays a role. Yes, radiation also plays a role. **Step-by-Step Explanation:** Blowing increases the evaporation of water from the tea surface. Evaporation absorbs latent heat from the liquid, cooling it faster. Radiation also contributes to cooling, and in a spoon the surface area-to-volume ratio is high, so radiation is significant. Together, evaporation and radiation cool the tea [citation:13].

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