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The human brain consumes about 20.2 W of power under normalconditions, though mo

ID: 1753143 • Letter: T

Question

The human brain consumes about 20.2 W of power under normalconditions, though more power may be required during exams. Howlong can one candy bar (246 Calories per bar) power the normallyfunctioning brain? (Note: The nutritional Calorie is equivalent to1000 calories (1 kcal) as defined in physics; 1 kcal = 4186J).

What I did was convert cal to J and got 1029.759J. Then Ithought I would divide that by the power to get the time the candywould power the brain. I got 50.978 s. But that isincorrect...where am I going wrong?

Explanation / Answer

Energy is the candy bar is E= 246 x 4186 = 1,029,756 J P=E/t then t=E/P= 1,029,756 /20.2 = 50978 s or 14.2hours

"multiply the calories by the joules"
since
1 kilo-calorie = 4186 Joules