Calculating Metabolic Energy Expenditure for Running and Walking

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Homework Help Overview

The discussion centers around calculating the metabolic energy expenditure for a 68 kg person running and walking at specified speeds and durations. The subject area involves concepts from physics related to energy, work, and metabolic power.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the relationship between metabolic power and energy expenditure, questioning the completeness of the provided information. Some raise concerns about factors like vertical displacement and acceleration that may affect energy calculations.

Discussion Status

Participants are actively engaging with the problem, with some providing insights into the necessary formulas and unit conversions. There is an acknowledgment of the need for additional information to accurately calculate the energy expenditure, and various interpretations of the data are being explored.

Contextual Notes

There are constraints regarding the information provided, particularly the lack of details on vertical displacement and the mass of limbs involved in the calculations. Participants also note the importance of using consistent units for accurate results.

dismalice
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Homework Statement



How much metabolic energy is required for a 68 kg person to run at a speed of 15 km/h for 12 mins in kJ?
Part B
How much metabolic energy is required for this person to walk at a speed of 5.0 km/hr for 36 mins in kJ?

Homework Equations



E=W (+Q)
W= FD
e=1/2 mv^2

The Attempt at a Solution


W_1 = ~ 666.4 N 15
V = 4.17 m/s

E= 140004.823
 
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This looks interesting but the answer can't be found from the information given. For instance, some of the energy goes to lifting the person between steps - so we need to know how high the body goes and how many times per minute. More energy is used to accelerate the legs and feet (which stop at each contact with the ground, don't they?), so we would need to know the mass of the feet and legs. Do you have formulas for estimating these things or perhaps some overall empirical formula for the power needed?
 
This is all the information that is given.
 
Can anyone else assist me with this problem?
 
I found data in the book that states RUnning at 15km/hr takes 1150W of Metabolic Power. I converted 1150W/H to equate to 19.167 W/minute then multiplied this answer times 12 mins and was unable to find the answer. Any ideas?
 
Much easier with that extra info!
1150 W is the power. It does not make sense to express it as 1150 W/H.
You will need a formula to find the work or energy given the power.
And you will need to be careful with the units. Best advice is to go with MKS units (time in seconds). Note that the answer is to be expressed in kilojoules rather than the standard Joules.
 

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