Energy content of food: Chadwick eats a Tim Horton\'s chocolate chip muffin cont
ID: 1467382 • Letter: E
Question
Energy content of food:
Chadwick eats a Tim Horton's chocolate chip muffin containing 16 g of fat, 69 g of carbohydrates, and 5 g of protein. Worried about “freshman-10”, he decides to burn off some calories with a bike ride. He produces a mechanical output of 168 W riding his bicycle. Assume that the body is able to convert chemical energy into mechanical output with an efficiency of 25% when cycling. Calculate how long he must ride (in minutes) in order to use up the calories contained in the snack.
Energy Content (kcal/g)
fat 9
carbohydrates 4
protein 4
alcohol 7
Explanation / Answer
total calories = sum of (energy content * mass of item)
total calories = 16 * 9 + 69 * 4 + 5 * 4
total calories = 440 kcal or 1.841 * 10^6 J
efficiency = 25% so,
mechanical input * 25 / 100 = mechanical output
mechanical input * 25 / 100 = 168
mechancal input = 672 W
power = energy / time
672 = 1.841 * 10^6 / time
time = 1.841 * 10^6 / 672
time = 45.6597 min
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