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B Calculated G force and don't know what to do now (punch force)

  1. Jul 27, 2016 #1
    i have calculated the g forces for my favorite comic book character doomsday to see how hard he punches and i know that the equation is V^2/R and i finally finished my equation and my answer is
    1.39160521 × 10^23 hertz what does this answer mean and what do i do know to find the amount of G forces and let me know if this is the right thread level for g forces
  2. jcsd
  3. Jul 27, 2016 #2


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    Staff: Mentor

    Show your calculations or we won't have any idea what you've done.
  4. Jul 27, 2016 #3


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    Homework Helper

    Please show your working :-)
  5. Jul 28, 2016 #4
    “Tests with Air force pilots have shown, that they could identify the plane on a flashed picture that was flashed only for 1/220th of a second.”

    That is identifying. So it's pretty safe to say, that recognizing, that SOME light was there is possible with 1/300th of a second.”

    First, let's assume your field of vision on a clear horizon at ground level is 2.5 miles in either direction. Also, let's assume that the statistic quoted above that you probably couldn't recognize something if it flashed for just 1/300th of a second is true.

    So a plane travelling 5 miles in 1/300th of a second would travel at 1,500 miles a second or 5.4 million miles an hour. That's about .8% the speed of light.

    5.4 million miles an hour divided by the normal speed a human runs is

    192,857 times faster to be useable

    And At it's closest, Pluto is 2.66 billion miles (4.28 billion km) from Earth, and at its furthest 4.67 billion miles (7.5 billion km). This means that Superman is travelling somewhere between 238 and 418 times the speed of light lets take 418 then

    418 times 192,857

    80,614,226 times the speed of light

    speed of light in meters per second 299,792,458

    so 299,792,458 times 80,614,226 is

    24,167,537,000,000,000 m/s

    So the equation for g forces is Velocity in m/s with that number squared divided by the radius in meters

    So if you make 24,167,537,000,000,000 m/s squared it is


    By using a photo of doomsday, doomsday is 4.62500 inches as the picture at least and using a unit I call DH which stands for doomsday heads which the size of his head is around 0.6875 inches

    So 4.62500 divided by 0.6875 inches

    That means there is 6.72727273 doomsday heads in his whole body so let’s put it down to 6.73 so its easier (this is the closest I can get I’m not a master at decimals so the whole thing might be almost a sliver off)

    And the actual height of doomsday is 8ft and 10 inches

    So 8 ft 10 inches divided by 6.73 is

    So doomsdays actual size of his head is 1 foot 3¾ inches

    So we saw how many DH can be on one arm and it is exactly 3 and 1/5

    So 1 foot 3¾ inches times 3 and 1/5 is

    4 feet 7⅛ inches or 4.59375 feet

    So let’s make this easier and sat his arm is 4.59 feet

    So that means his arm is 1.399032 meters

    Let’s simplify it so it is 1.4 meters

    So know let’s use this info and complete the equation

    So 194,824,730,000,000,000,000,000/1.4

    1.39160521 × 10^23 hertz

    links because some of this stuff other people have kind of answered


  6. Jul 28, 2016 #5
    ok here is the equation V^2/R is velocity in meters per second squared divided by the radius in meters I did this calculation used a google as a calculator and ended up with hertz
  7. Jul 28, 2016 #6
    Quite a few issues with your calculations.
    Why did you use this formula? Why have you used his arm length as the "radius"?
    I didn't get this also. What do you mean by "useable"?
    Here you've exceeded the speed of light, which isn't possible (even in theory). But, since this is Superman (fiction) we're talking about, let's just ignore the laws of relativity.
    It's not that simple to apply these equations to human actions. A punch is a complicated thing. Knowing how fast Superman moves isn't enough to know the force of impact; you'd also have to know how he conducts his arm during the punch (or at least the depth of the dent caused by the punch).
    As for the units, g-force is measured in g's (the g stands for acceleration due to gravity; roughly equal to ##9.8m/s^2##). I suppose you know that g-force isn't actually a force, rather it's an acceleration.
  8. Jul 29, 2016 #7


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    That's not an equation for force of any type because it doesn't have the right dimensions. ##v^2/r## is an acceleration, namely the centripetal acceleration needed to keep an object in a circular orbit of radius ##r##. It has nothing to do with what you're trying to calculate, so it's not surprising that you're getting nonsensical results.

    You're looking for the "force of a punch". For that you can start with the definition of what a force is, from Newton: ##F=ma##. There are two ways you can go from there:
    1) Estimate the mass of the fist and how much its speed changes when it strikes the punched object.
    2) Estimate the mass of the punched object and how much its speed changes when it is struck by the fist.

    You will use the speed change to calculate the acceleration, but to do that you need to know long it takes for the speed to change. That can be calculated from the initial and final speed and as aniruddha said, "the depth of the dent caused by the punch".
    Last edited: Aug 1, 2016
  9. Jul 31, 2016 #8
    ok I found out how to calculate it here https://www.physicsforums.com/threads/calculating-g-force.611116/ and I am ignoring the laws of physics since it passes the speed of light and I meant at that one part where I said useable I meant unseable I also just realized that I need to find out the exeleration of the object he Is hitting and I new it wasn't a force it was an exelleration but I wasn't thinking of that so dang it I have to do most of the equation over lol I will send you the results when I'm done
  10. Jul 31, 2016 #9
    and I just read what nugatory said and I need to do the whole thing over again lol
  11. Jul 31, 2016 #10
    so I'm going to so option number 2 where you said
    "2) Estimate the mass of the punched object and how much its speed changes when it is struck by the fist."
    know what is the equation to this and I am new to equations so explain what the symbols mean
  12. Aug 1, 2016 #11


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    Staff: Mentor

    So what are your estimates of the mass of the punched object and how much its speed changes when struck by the fist?
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