Essential University Physics (3rd Edition)
3rd Edition
ISBN: 9780134202709
Author: Richard Wolfson
Publisher: PEARSON
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Textbook Question
Chapter 6, Problem 33E
A typical human diet is “2000 calories” per day, where the “calorie” describing food energy is actually 1 kilocalorie. Express 2000 kcal/day in watts.
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A food calorie is a unit of energy such that 1 food calorie = 4184 J. This means that a person that burns energy with a power of 4184 W would burn one food calorie every second. A more typical human power rate is 90 W (called the basal metabolic rate). At this rate, how many calories are burned per second (or alternatively, how many seconds does it take to burn 1 calorie)?
The food calorie, equal to 4186 J, is a measure of how much energy is released when food is metabolized by the body. A Milo Bar contains 180 food calories per bar. (a) If a 70-kg hiker eats one Milo Bar, 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? (b) If, as is typical, only 20% of the food calories go into mechanical energy, what would be the answer to part (a)? (NOTE: In this problem, we assume that 100% of the food calories that are eaten are absorbed and used by the body. This is actually not true. A person’s “metabolic efficiency” is the percentage of calories eaten that are actually used; the rest are eliminated by the body. Metabolic efficiency varies considerably from person to person.)
I'm trying to solve this question,
The record time for a Tour de France cyclist to ascend the 1100-mm-high Alpe d'Huez is 37.5 minmin. The rider and his bike had a mass of 65 kgkg. At the average speed of the ride, the metabolic power to ride on level ground would be 700 WW. To this, we must add the power to make the climb.
What was his total metabolic power?
I arrived at 1125W, but the answer is not right. How do I need to approach this problem?
Chapter 6 Solutions
Essential University Physics (3rd Edition)
Ch. 6.2 - Two objects are each displaced the same distance,...Ch. 6.3 - Three forces have magnitudes in newtons that are...Ch. 6.4 - For each situation, tell whether the net work done...Ch. 6.5 - Prob. 6.4GICh. 6 - Give two examples of situations in which you might...Ch. 6 - If the scalar product of two nonzero vectors is...Ch. 6 - Must you do work to whirl a ball around on the end...Ch. 6 - If you pick up a suitcase and put it down, how...Ch. 6 - You want to raise a piano a given height using a...Ch. 6 - Does the gravitational force of the Sun do work on...
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