We often cut a watermelon in half and put it into the freezer to cool it quickly. But usually we forget to check on it and end up having a watermelon with a frozen layer on the top. To avoid this potential problem a person wants to set the timer such that it will go off when the temperature of the exposed surface of the watermelon drops to 3°C. Consider a 25-cm-diameter spherical watermelon that is cut into two equal parts and put into a freezer at 212°C. Initially, the entire watermelon is at a uniform temperature of 25°C, and the heat transfer coefficient on the surfaces is 22 W/m2·K. Assuming the watermelon to have the properties of water, determine how long it will take for the center of the exposed cut surfaces of the watermelon to drop to 3°C. Answer: 46.7 min

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A: The heat will be, Q=McΔT Also, Q=mLv Thus we have, ΔT=mLvMc

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A: See below

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Q: dermatologist often remove small precancerours skin lesions by freezing them quickly with liquid…

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Q: Randy is nervous oboOut Physics 102 exam that he can't concentrate. To relax he, goes to Starbucks…

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Q: How much hea Express your Q = V

A:

Q: The "steam" above a freshly made cup of instant coffee is really water vapor droplets condensing…

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Q: heat transfer rate

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A:

Calorimetry

Measuring the heat transferred during chemical reactions or other physical processes is known as calorimetry. It comes under the branch of thermochemistry.