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Homework Help: Applying Physics to my workout

  1. Mar 14, 2005 #1

    First off this isn't a book problem so I'm not really sure if it can be solved. I just kinda dreamed this up one day while deciding to count the calories in my lunch + breakfast. It should work..if I thought everything through, and I can live with a few simplying assumptions. Anyhow, I totaled the calories I eat in 2 meals, and I want to find how many miles I would have to run to "burn" of these calories(Springbreak saw me gain 5lbs :yuck:).

    Ok so,

    If my total calories are 1,146c, so that's 4798j. (1calorie = 4.187j)
    My distance is 1mi or 1609m
    My weight is 217lb or 97.65kg

    My question is, if I find the work done by moving a 97kg mass 1609meters in joules, and then dividing by my calorie intake (in joules)...does this give me what I want?

    If so,

    Can anyone give me some pointers as to setting up a free body diagram/ finding the work

    If not,

    Could some one point out the holes in this problem, or do I scrap it completely


    All I want to do is find how many miles I would have to run to burn the calories aforementioned.

    Thanks in advance
  2. jcsd
  3. Mar 14, 2005 #2
    Sorry, but there is a problem. Work is only down on an object when a mass is accelerated. If you run at a constant speed, there is no work being down. Well not really, your legs are moving up and down, your body is producing heat, and there is work done against friction (more than you would think). What you need to do is find studies that have tested the work output of runners. There are charts called basal metabalism charts (spelled something like that anyway) that will give work done versus hard excercise. This will give you a much more accurate calculation.
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