The lowest point in Death Valley is 85 m below sea level. The summit of nearby M
ID: 1266029 • Letter: T
Question
The lowest point in Death Valley is 85 m below sea level. The summit of nearby Mt. Whitney has an elevation of 4420 m. What is the change in potential energy of an energetic 65 kg hiker who makes it from the floor of Death Valley to the top of Mt. Whitney?
Convert your answer to the customary units you are used to for measuring food energy, either kilocalories or kJ. (1 kcal = 4180 J.) Does the change in potential energy reflect the amount of food energy that a hiker must consume to make this trek? If not, where does the rest of the energy go?
Explanation / Answer
Part A)
PE = mgh
PE = (65)(9.8)(4420 + 85)
PE = 2.87 X 106 J
That is 2.87 X 103 kJ or 686 Kcal
No, this is not the food represented. Some of the food energy goes to simple body processes such as breathing, your heart beat, your eyes blinking, etc. Additionally, your body is only 25% efficient (as an average), so in reality you would have to eat 4 times that amount of food to have that much total energy.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.