Energy Question

Question

An "energy bar" contains 18 g of carbohydrates. If the energy bar was his only fuel, how far could a 68 kg person walk at 5.0 km/h?

Answer 1

First of all, to clarify, the carbohydrates mentioned are probably sucrose, which is the most used sugar in the food industry. According to the USDA, though, the energy content of 100g of sucrose, glucose, and fructose is 1620kJ for each sugar, so we'll use this to determine our energy content of the energy bar.

Second, recall that the definition of work is force multiplied by distance. The force involved is the gravitational pull (F = mg, where g = 9.8m/s²).

So, the game is to determine the energy in the bar, set that as the upper limit on the energy expended, and back out the distance walked using that amount of energy.

I'll let you set up the equations and do the calculations, but I got 0.44km. Hope this helps!