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G force question

  1. May 16, 2007 #1
    Hello,

    Im trying to calculate the amount of G force generated from a golfswing for example. Let's say the swing is carried out with an acceleration of 26rad/sec, and that it is perfectly circular ;)

    Im using formula a = w^2 *r; If my armls add 40cm and I want to know the G force 6cm below my grip...

    a = 26^2 * 0.23 = about 155, divided into 9.82 meters/sec = 16G ,

    That sounds a bit high to me so I would like to know if I am doing something wrong here...

    Br
    /Markus
     
  2. jcsd
  3. May 16, 2007 #2

    FredGarvin

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    From what you have given, the only thing I see wrong is that you used your arm distance plus 6 cm as a diameter and not a radius. I assume that you are considering your shoulder as the center of the circle.

    Your angular velocity (not acceleration) of 26 rad/sec is moving pretty quickly. It's almost 250 rpm.
     
  4. May 16, 2007 #3
    Aa that's right, so the correct value should be more something like 26^2*0.46 then... that's more like 30G,

    I got the value 26rad/sec from some golfing website, it might be wrong, but the pro's can reach a speed of 100mph at the tip of the club, not sure how to convert that into rad/sec though.

    /Markus
     
  5. May 16, 2007 #4

    FredGarvin

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    It wouldn't be to tough to do an experiment to see how good your numbers are. A spring scale and a weight to mimic the club would do it.

    30 G sounds a bit high, but not totally unreasonable.
     
  6. May 16, 2007 #5

    AlephZero

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    100 mph = 160 km/h = 160*1000/3600 m/s = 45 m/s

    Angular velocity = v/r where r is the total radius (length of arm + club). From the size of a normal person, r must be a bit less than 2m, say 1.8m

    Angular velocity = 45/1.8 = 25 rad/sec.

    So your numbers seem consistent.

    The golfer doesn't actually feel the "G" value as an acceleration, he/she only feels the force. An acceleration of 30G on a 1Kg object gives a force of 30 Kgf. (I'm not a golfer but 1 Kg sounds too much for the mass of a golf club). A fit person can easily lift his/her body weight with his/her arms, so a 30 Kgf force seems quite reasonable.
     
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