Question

You run a 26.2 mile marathon race (42.2 km) at a steady 15 km/h pace. While running at this pace, your metabolic power is 1,127 W. If a single apple provides 480 kJ of metabolic energy, how many apples should you eat to provide the full amount of energy required to run the race? Your answer may not be a whole number -- for example, 1.23 apples. Include several significant figures in your calculations and your answer to avoid rounding error. Do not include units with your answer.

Answer 1

Given that speed of running = 15 Km/h

Distance of marathon =42.2 km

So the time taken to finish the marathon = distance/ speed = 42.2/15 . Hours

The power to run the marathon = 1127 W

= 1127 Joules per second

So the energy required to run 1 hour of marathon = 1127*60*60 = 4057200 Joules.

So the total energy required to run for (42.2/15) hours= 4057200*(42.2/15)

E = 11414256 Joules.

The enery given by 1 apple = 480 KJ

= 480000 Joules

So number of apples needed to give sufficient energy= Total enery needed/ energy from 1 apple

= 11414256/480000

= 23.7797 Apples

So the answer is 23.7797.

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