1.

How much heat is produced by a human body?(a) 200 W(b) 100 W(c) 50 W(d) 0.5 WI had been asked this question in an online interview.Question is taken from Basic Energy Concepts topic in chapter Energy Balance of Bioprocess Engineering

Answer»

The CORRECT choice is (b) 100 W

For explanation: A man doing no or very little physical work needs about 2,000 kcal (or less) of energy in his daily food. The body converts this energy almost entirely into heat.

1 day = 24 x 60 x 60 s = 86,400 s 1 cal = 4.2 J

Hence, 2000 kcal/day = 2000 × 4.2 kj/day = \(\frac{8.4 \,Mj}{86600s}\)

= 100 j/s = 100 W

We see that a HUMAN body doing no work is EQUIVALENT to a heat source of about 100 W – the equivalent of a GOOD bulb.



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