The food calorie, equal to 4186J , is a measure of how much energy is released w

Question

The food calorie, equal to 4186J , is a measure of how much energy is released when food is metabolized by the body. A certain brand of fruit-and-cereal bar contains 140 food calories per bar.If a 69.0kg hiker eats one of these bars, how high a mountain must he climb to "work off" the calories, assuming that all the food energy goes only into increasing gravitational potential energy?

If, as is typical, only 20.0% of the food calories go into mechanical energy, what would be the answer to part (a)?

Explanation / Answer

Energy in joules = 140 x 4186 = 586040 Joules a. Now, we have, E = mgh 586040 = 69 x 9.8 x h Height = h= 866.667 meters b E = 0.2 x 586040 = 117208 Joules Now, E = mgh' 117208 = 69 x 9.8 x h' Height = 173.33 meters

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