Problem 63P

CE Predict/Explain (a) If you rub your hands together, does the entropy of the universe increase, decrease, or stay the same? (b) Choose the best explanation from among the following:

I. Rubbing hands together draws heat from the surroundings, and therefore lowers the entropy.

II. No mechanical work is done by the rubbing, and hence the entropy does not change.

III. The heat produced by rubbing raises the temperature of your hands and the air, which increases the entropy.

Solution 63P

Step 1 of 2

We have to choose the correct statement from the given set.

a) If we rub our hands together, due to the friction, heat will be generated and it will be added to the surroundings. Therefore, the heat of the surroundings will increase. The equation for the change in entropy is,

Where, - Change in heat

- temperature of the system

So, it is clear that the entropy of the universe will increase since the excess heat is added up to the surroundings since we rub our hands together.

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b)