Author:
Johanna O'Day
Subject:
Engineering, Biology
Material Type:
Module
Level:
College / Upper Division, Graduate / Professional
Tags:
  • Biomechanics
  • Walking
    License:
    Creative Commons Attribution Non-Commercial Share Alike
    Language:
    English

    Ch. 2 Problem 3

    Overview

    Chapter 2 Problem 3, takes less than 15 minutes to complete by hand. No computer necessary.

    2.3

    Energy expenditure in walking

    95 Cal * 4181 J/Cal * 0.60 = 238,488 J

    Fr = 0.25 = v**2/(9.81*0.9) --> v = 1.49 m/s

    From Figure 2.9 and using the Browning 2006 curve, a walking speed of 1.49 requires a cost of transport of ~3 J/(kg*m).

    3 J/ ( kg * m) = 238488 J/(70 * m) --> distance traveled = 1136 m

     

    Energy expenditure in walking

    A medium-sized apple contains about 95 Cal (note that 1 Cal = 1 kcal ≈ 4184 J). Assuming 60% efficiency in conversion of an apple to available energy, how far can a person weighing 70kg walk using all of the apple’s energy while maintaining a comfortable pace with Froude number = 0.25? Assume a leg length of 0.9 m.