Calculating Metabolic Energy Expenditure for Running and Walking

[dismalice]

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

 

[Delphi51]

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?

 

[dismalice]

This is all the information that is given.

 

[dismalice]

Can anyone else assist me with this problem?

 

[dismalice]

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?

 

[Delphi51]

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.