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Centripetal Pump - Unweighting as you drop?

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  • Centripetal Pump - Unweighting as you drop?

    Just been looking at this video and was surprised when they said that the 'Sam Snead Squat' causes the weight readings to get less (ie.unweighting) as you drop down. I always thought it was the opposite . Shows that you can learn something new every day.






  • #2
    Did they tell you why that is?? Because that is the key to the pump in the golf swing.

    Comment


    • Schrodinger
      Schrodinger commented
      Editing a comment
      No - they never explained why and I've always tried to feel the opposite. I'm sure there is a physics explanation somewhere. I'll search it out.

  • #3
    Found it ! The internet is amazing but now that I think about it , I feel weightless in an elevator when it goes down but never thought of that phenomenon when doing a squat

    http://ffden-2.phys.uaf.edu/211_fall...the-squat.html




    Power Example
    This free body diagram shows the forces involved in the squat movement. For the purposes of determining power, we will use the following values:
    • m = Mass of load = 150kg
    • d = Distance travelled = 0.96 meters (note: this value is for only one direction of movement and will be doubled to determine the total distance that the load must travel)
    • g = Gravity = 9.8 m/s^2
    • t = Time to move load = 2.2 seconds
    • a(d) = acceleration of the load in the downward direction = 1.2 m/s^2
    • a(u) = acceleration of the load in the upward direction = 0.8 m/s^2`
    Lowering
    Work = m(g-a)d = 150kg(9.8m/s^2 - 1.2m/s^2)(0.96m) = 1,238.4 J (WORK = Force x distance moved in the direction of the force , therefore Force = m (g-a) (where 'a' is the acceleration in the downward direction)

    P1 (Power)= (1,238.4 J)/(2.2 sec) = 562.9 Watts

    Raising
    W = m(g+a)d = 150kg(9.8m/s^2 + 0.8m/s^2)(0.96m) = 1,526.4 J
    P2 = (1,526.4 J)/(2.2 sec) = 693.8 Watts

    Total Power
    P1 + P2 = 562.9 W + 693.8 W = 1,256.7 Watts are exerted by the lifter in lowering and raising the load.

    This is a very simplistic determination and fails to take into account the variable levels of acceleration that occur at different points throughout the lift. It also fails to take into account the work done to move the lifters' own body weight. However, it gives a basic idea of the amount of power exerted by a lifter performing a squat.

    Comment


    • Schrodinger
      Schrodinger commented
      Editing a comment
      I suspect its easier to perceive if one imagined you were upside down and supporting a heavy object on your legs , then allowed your knees to bend to allow that object to drop slightly to the ground . It would feel lighter , therefore the force between the object and your feet would be less as you did an 'upside down squat' action.

    • COSTA103
      COSTA103 commented
      Editing a comment
      Hi guys,
      I must admit that I've always had sort of that "elevator-drop" since forever?
      I think I copied it from a little kid (me) standing up on a swing trying to "pump" to get the swing to go HIGHER?
      dude abides

  • #4
    Concerning the squad, I like to add a typical feeling,you know, WIG is a lot of feeling.
    Recently Shawn Sawn mentioned in a video with a student ‘loose in the caboose ‘.
    If you notice the angle at the right hip at adress, how many of us get rid of that angle at the end of the backswing?
    Goes together with ‘early extention’ and missing counterweight.
    Look at a typical swing from Shawn at that point, the rear leg is bolted into the ground, ready to jump forward/up.
    So, if you maintain that angle for the hip area at the end of the backswing, typically you really feel the pressure on the rear foot.
    Means, if you squad don’t look only at the foot alone, the angle in the hips must be still there. If not, how shall you jump?
    It is really astonishing how much effortless power and body control is happening then.
    And, notice, if you keep that hip bend at the end of the back swing, how often you are in perfect balance?
    No need to rush (short circuit-out of balance).

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    • #5
      So as we squat we reduce the feeling Gravity? See the demonstration and explanation starting at minute 4.
       

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      • #6
        Thanks Gary!
        Not only was this Brian Greene video fun, it was brilliant.
        Someday, why I think that will become more clear...(perhaps "kid" will chime in and drag more of it out of me? like he always seems to...

        I wish that I could "like" this MORE than ONCE?

        dude abides
        "OLD" Forum Participation

        Entry Date: 18-JAN-2011
        Posts: 1813
        Thank You: 1048

        "Be water, my friends"

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