A 60 kg hiker wishes to climb a mountain an ascent of 1500 m. a) assuming she is

Question

A 60 kg hiker wishes to climb a mountain an ascent of 1500 m.
a) assuming she is 20% efficient at converting chemical energy from food to mechanicmal work and that essentially all mechanical work is used to climb , roughly how many bowls of cornflakes ( standard serving size 1 ounce, 100 kcal) should the hiker eat before setting out.
b) in fact , the extra energy does not warm the hiker's body, instead it goes into evaporating water from her skin. how many litres of water should she drink during the hike to replace the lost fluids? At 25 degrees celcius the latent heat of vaporization of water is 580 cal /g
c) A 60 kg cyclist can climb the same ascent on his 8 kg bike, without going though calculations again show which assumptions would be different and how it would change the answer of a

Explanation / Answer

Potential Energy = mgh = (60) * (10) * 1500 = 900000 J

a) Energy Conversion Factor = 20% = 0.2

Chemical Energy from Food = 0.2 * 900000 = 180000 J

1 Kcal = 4184 J

Hence bowls of cornflakes = 180000/4184 = 43.02

Hence number of bowls of cornflakes required = 43

b) Energy lost making water evaporate = 0.8 * 900000 = 720000 J

Latent heat of vaporization of water = 580 cal/g = 2426.72 J/g

Amount of water required = 720000/2426.72 = 296.69 gms

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