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Help With Mechanics Problem

  1. May 17, 2003 #1
    One of my friends is really into exercising. He also knows someone who can squat around 600lbs. My friend believes that by doing one legged full range of motion jump squats he can become strong enough to squat 600lbs (this would be a two legged squat also with a full range of motion).

    Since my friend is using one leg and the other fellow is using two, we believe he will need to produce twice as much force as the other man.

    We also know it takes the two legged squater about 3s to complete his squat.
    For my friend to complete a jump squat we estimate it to take him about .5s or less.

    We also believe that the 2 legged lifter is lifting about 4/5 of his body weight + the actual 600lbs of weight he is using.
    And my friend will be lifting more of his body weight than the other man because it is with one leg, so we will estimate it to be about his full body weight.

    The 2 legged squater weighs about 125kg.
    My friend weighs about 61kg.

    We also have estimated the bottom of a squat to the top of a squat's range of motion to be .44m.

    So what we want to know is what distance my friend will have to jump starting from the bottom of the squat position to the top of his jump's trajectory, to be creating the same amount of force someone who squats 600lbs is.

    I know this seems like a real pain in the ass problem, and I don't even know if it can be solved with the given information, nor am I sure how to solve it correctly. So please offer any input on the problem that you can, and if you can actually solve it, it would greatly be appreciated.

    Thanks a ton,
    Dan
     
  2. jcsd
  3. May 17, 2003 #2
    Hmm, can't be done I think. (welcome to PF by the way)

    The reason is the same you're supposed to lift slowly.... when you're friend is jumping, his goal is to get as much upward speed as possible as quickly as possible. This means that 1) he is using his fast-twitch muscles, and 2) it doesn't matter what portion of the squat he exerts the most force in. For real squats, you just have to be able to exert slightly more force than the weight, during the lowest part. So it's an entirely different thing... there is probably a relationship but it's going to be really complicated and not likely reliable.

    Just have your friend keep maxing out. :wink:
     
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