Need help with a problem involving work and calories

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SUMMARY

The discussion revolves around calculating the food calories required for a 70 kg person to run up a flight of stairs with a vertical height of 6 m, using an efficiency of 10%. The potential energy (P.E) is calculated using the formula P.E = mgh, resulting in 4116 Joules. After converting this energy into calories, the user determined that approximately 9830 calories are needed, but the answer key indicates only 9.9 calories (Kcal). This discrepancy highlights the importance of understanding the distinction between calories and kilocalories in energy calculations.

PREREQUISITES
  • Understanding of potential energy (P.E) calculations
  • Familiarity with the concept of efficiency in energy conversion
  • Knowledge of calorie and kilocalorie definitions
  • Basic algebra for solving equations
NEXT STEPS
  • Study the conversion between Joules and calories, specifically focusing on food calories (Kcal)
  • Learn about the principles of energy efficiency in physical activities
  • Explore the implications of energy expenditure in exercise physiology
  • Investigate common misconceptions regarding calorie calculations in nutrition
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Students in physics or exercise science, nutritionists, fitness trainers, and anyone interested in understanding the relationship between energy expenditure and food intake.

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Homework Statement


A person whose mass is 70 kg runs up a flight of stairs through a vertical height of 6 m. If she uses her food with an efficiency of 10%, how many food calories does she have to consume to do this work?

Homework Equations



P.E=mgh=W

(Output/input)*100 = Efficiency

The Attempt at a Solution



I assumed that mgh=w because there is not kinetic energy at the top, so I just solved for mgh and got 4116J. I converted that into calories and found the input using the formula above, an I got ~9830 cals. When I looked at the answer key it said 9.9 cals( not Kcals)
 
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A food calorie is a Kcal. (You can look it up.)
 

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