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Stirring up trouble

My son was vigorously stirring a very hot cup of drinking chocolate as he thought...

My son was vigorously stirring a very hot cup of drinking chocolate as he thought that would cool it down. I said stirring the liquid was adding energy to it. Who is right? If him, what鈥檚 the best speed to stir at to cool the hot chocolate? And if me, is it possible to heat it up by stirring very fast?

Hamish Steiner Cooma, New South Wales Australia

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