mythbusting dorks strike again with wild wisdom!

Discussion in 'Computer Support' started by richard, Nov 26, 2009.

  1. richard

    richard Guest

    The discovery channel airs a program called "mythbusters" which
    investigates the reality of myths. The two hosts, who claim to have 30
    years of experience as dunce, uh I mean stunt, men, some times leaves me
    wondering of their honesty. And intelligence.

    So on tonight's show the two clowns are jumping into a dumpster ?
    OH please. Like this scene is so old it's pathetic. I mean like these guys
    never did this as stunt guys before? Yeah right.

    So off to go stunt school they go? Huh? "We're professionals. We have
    experience!". At what?
    Like I've seen people jump out of helicopters onto airbags from 200 feet or
    more. The show wastes over 10 minutes of time of them looking around at
    various materials found in dumpsters. Like who cares?

    Ok so finally it comes time for them to actually jump. Onto an airbag from
    a mere 13 feet. Hell, I used to do that as a kid.

    They routinely their assistant "dummy" and hook him up with all kinds of
    gadgets. The one host concludes from the data, "From a 20 foot fall you
    would generate 11.4g's..........".

    WHHHHHHAAAAAAAAAATTTTTTTTTTTTTT?

    Yes sir, that is what he said. 11 point 4 gees.
    Can we say HORSEHOCKEY?

    A roller coaster ride falling from 200 feet only produces at the most, 3
    gees. A jet fighter pilot has to wear a gee suit to combat a mere 7 gees.

    Now don't get me wrong, the show is mostly entertaining and educational.
    It's just that sometimes these two dorks get things totally wrong.

    If you must know, a "g" is the force applied against your body during
    certain events. 1g is normal. 2g means it takes twice as much force from
    your body to do the same work. 11 point 4g? Hell, you could barely move.
     
    richard, Nov 26, 2009
    #1
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  2. richard

    richard Guest

    I do not rely on the wikipedia for factual information.

    What people refer to as a "G" force when applied to roller coaster riding,
    is not actual fact. 7G on a coaster? Prove it. Scientifically.

    If the fall produced 11.4G from a mere 20 feet, then a parachutist falling
    from a plane at 10,000 feet, at a speed of 120mph, would not be able to
    pull his rip cord. Let alone survive the jump.
     
    richard, Nov 26, 2009
    #2
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  3. richard

    Mike Easter Guest

    richard wrote:
    <mythbuster TV show about dumpster diving>

    disclaimer: I didn't see the show. I had to go look up what it showed
    and said.

    What I read: they dropped a dummy into a cushioned dumpster from 20
    feet to generate shock force and measure it with an accelerometer (idea
    triggered from some show stunt)

    Math: when you - the dummy - are falling, our 1g gravity is affecting
    you and accelerating you at 1g for a short time, so you gain speed by
    the force of gravity.

    When you stop (suddenly), the dummy's accelerometer measures the shock
    forces exerted on you in g. Thus, if your total body stops in the
    tiniest instant, such as if a dummy were hurled at a brick wall at that
    speed, the g forces would be much greater over the extremely short
    stopping distance and time than if your body's stoppage were 'cushioned'
    so that the stopping force could be spread out over several instances -
    fractional milliseconds - and cushion distances.

    What I read about the mythbuster episode said that the design of the
    cushion - professional airbag - was supposed to be able to handle 11.4
    g/s, but I don't know exactly what that 'means' contrasted with shock
    forces or 'jerk' of stopping as described in the wikipedia, but I do
    understand (what it means) that the dummy experienced 9.9 g/s shock
    force according to its accelerometer.

    The wiki talks about short g-force durations and 'jerk' in its article.
    It (also) says that Indy car drivers have survived 'shock' or 'jerk' of
    over 100 g in crashes.

    Even if you aren't going very fast, if your stop is abrupt, some g
    forces are going to be registered on your accelerometer. How many
    depends on how your stop is cushioned. 9.9 g/s in this shock/jerk/
    context aren't actually very many (or for very long), whereas it is a
    fair amount of trouble to generate sustained 10 g/s in something like a
    centrifuge.
     
    Mike Easter, Nov 26, 2009
    #3
  4. richard

    Mike Easter Guest

    I don't actually want to watch another video. I'm not a video kinda
    guy. When I wanted to research this mythbuster issue, the 'net was
    'full of' mythbuster videos which I had to 'climb over' to find out what
    was really going on.

    I would rather read an article about whatever point you want to make.
    Find one of those and select your sentence/point from that article.
     
    Mike Easter, Nov 26, 2009
    #4
  5. richard

    Aardvark Guest

    It didn't cross your mind, of course, that the 11.4G was, in fact, the
    maximum gravitational force measured and that level of force was only
    maintained for a fraction of a second at the moment of impact?

    Of course it didn't, sto0pid.

    During any free fall, the force acting on the object falling is only ever
    1G. Depending on the speed of the body on impact, the G-force it
    experiences could be extremely high.
     
    Aardvark, Nov 26, 2009
    #5
  6. richard

    Aardvark Guest

    Why does he persist in watching that programme when he obviously doesn't
    have the education or intellectual wherewithal to understand the scientific
    principles they sometimes deal with?
     
    Aardvark, Nov 26, 2009
    #6
  7. richard

    Desk Rabbit Guest

    Go and research the term "Terminal Velocity" and then come back and
    apologies to everybody in the world for your stupidity.
     
    Desk Rabbit, Nov 26, 2009
    #7
  8. richard

    Desk Rabbit Guest

    Read this and educate yourself (Hopefully)
    http://hypertextbook.com/facts/JianHuang.shtml
     
    Desk Rabbit, Nov 26, 2009
    #8
  9. richard

    Aardvark Guest

    "A man's gotta know his limitations"- 'Dirty' Harry Callahan in 'The Dead
    Pool'.

    :)
     
    Aardvark, Nov 26, 2009
    #9
  10. richard

    Mike Easter Guest

    DeadPool was a DirtyHarry, the last, but Magnum Force, the second, is
    the one generally credited with the limitations line.

    You would think that he would say it again in the 5th in the series,
    since it was so popular coming in the 2nd, just for fan appeal.
     
    Mike Easter, Nov 26, 2009
    #10
  11. richard

    Aardvark Guest

    Shit! Yer right Mike. My mistake.
    "Make my day, punk".
     
    Aardvark, Nov 26, 2009
    #11
  12. richard

    Mike Easter Guest

    "Come on, make my day." Sudden Impact

    "... you've got to ask yourself one question. Do I feel lucky? Well,
    do ya, punk?" Dirty Harry
     
    Mike Easter, Nov 26, 2009
    #12
  13. richard

    richard Guest

    As I understand what was said, the "g" forces were being measured during
    the fall. That was the point of the accelerometer. You can not make me
    believe that a human falling, from any distance, will create more than 2G's
    at the most.

    Granted, the sudden stop will create a short lived impact that may generate
    the force depicted, but is that really a "G"? I believe they are using the
    wrong terminology.
     
    richard, Nov 26, 2009
    #13
  14. richard

    Mike Easter Guest

    No. "Accelerometer" is the term being used to measure the forces of
    deceleration when the dummy stops - the shock of stopping.
    During the time of the falling on the planet earth, the body is being
    accelerated downward by a force of 1G.
    That deceleration 'force' (acceleration) is measured in g/s.
    There /is/ actually a problem with the terminology, but not in the way
    that is bothering you.

    There is a problem with the term 'g force' because g is not a force, but
    an acceleration. Units of force are not units of acceleration, as in F
    = ma where F is in units of force and 'a' is in units of acceleration.
    In the case of gravity acceleration, the a represents gravity.

    Another term is 'jerk'. Jerk is the rate of change of acceleration.
     
    Mike Easter, Nov 26, 2009
    #14
  15. richard

    Aardvark Guest

    You evidently don't.
     
    Aardvark, Nov 26, 2009
    #15
  16. richard

    Aardvark Guest

    9.81m/s/s

    That'll fox RtS.
     
    Aardvark, Nov 26, 2009
    #16
  17. richard

    Mike Easter Guest

    Oops. I meant to say that accelerometer is the term being used for the
    /device/ to measure the 'forces' caused by the deceleration when the
    dummy stops - the (severity of the) shock of stopping.

    That is, the accelerometer is functioning as a 'decelerometer' and the
    deceleration shock/jerk is being expressed in g/s.

    Since I didn't see the show, I can't say how I think they could have
    presented the episode in a more interesting way with the 'material'.

    For example; I think it might be interesting to compare some different
    decelerations with the same stuntman fall from say 40 or so feet, maybe
    60, so that the fall's deceleration would be considered to be definitely
    life threatening or not at all depending on how fast you stopped.

    Then you could have different kinds of stuntman deceleration devices.
    It is one thing to land on a pile of packing peanuts and yet another to
    land on one of those airbags which deflates at some well designed speed.

    Comparing devices whose purpose is the reduction of /real/ deceleration
    risk would be of interest to me -- not jumping into a cushioned dumpster
    from 20 feet. I've jumped off roofs and out of a tree from a height of
    20 feet. I don't think I would do that today.
     
    Mike Easter, Nov 26, 2009
    #17
  18. richard

    chuckcar Guest

    Because as they say "it's not the fall that kils you, it's the landing.
    Falling 200' and decelerating in 5' involves *far* less g forces than
    falling 3' and decelerating in .05". That's simple physics.

    If you are going 96MPH (a not unreasonable speed for a falling body) then
    you are going ~140 feet/second. If you stop moving in the space of 10'
    then you are decelerating at a rate of 14 ft/second^2 on average which is
    very close to .5 g (1g ~ 32ft/second^2). If it takes 1' to do it, then you are
    decelerating 10 times faster or ~5gs. If you do it in the width of a body
    - say 6" which is typical for something the body won't deform such as
    concrete or asphalt, then you are decerating at 10gs. 5gs is easily
    enough to make somone go unconcious without being prepared. 50gs *will*
    kill you instantly.

    The above are all average g forces during the entire landing. However due
    to the consistancy of a human body, there will be a different maximum g
    force endured.

    f=ma
    v=v0+at
    d=d0+vt+at^2

    You can do your own algebra.

    d=distance,v=velocity or speed,a=acceleration t=time and the "0" factors
    are the initial speed or distance involved. Velocity is the integral of
    distance wrt time, acceleration is the integral of velocity wrt time, distance
    is the derivative of velocity wrt time and velocity is the derivative of
    acceleration wrt time.

    Because it's TV, they don't show the math and fill the requirements
    thereof only partially with the "warning science content" bits. A
    personal peeve of mine and I'm certain of Mr. Savage's as well.
    Can you say "I know no physics whatsoever"?
    It doesn't stop moving. Hence it doesn't *reach* maximum force. All it does
    is turn in effect. From going down a "hill" to going up one. Or the other
    changes of direction. It's called centripital acceleration. Virtually all
    cars can only turn at up to 1g at best before they start sliding sideways.
    However if you have something on rails, the rails are stopping the car
    from moving "sideways" far more than a tire could.
    Their "science" isn't near rigorous as a lab would do it, and their "experiment"
    in harmonic destruction of bridges was never going to work, but their physics
    are spot on. They even confirm it with instruments.
    No. g force is the multiple of the force of gravity on earth that *any*
    object endures during *any* acceleration (postivive *or* negative). At
    11g you would be completely unconcious and likely have soft tissue damage.
    Jet fighters only go up to 10g maximum for momentary intervals.
     
    chuckcar, Nov 26, 2009
    #18
  19. richard

    Aardvark Guest

    Here's a link to explain what you're hinting at to RtS:

    < http://en.wikipedia.org/wiki/Euclidean_vector >

    You think he'll understand even a fraction of it?
     
    Aardvark, Nov 27, 2009
    #19
  20. I guess you've never been in a fighter. If you had, you the untrained
    civilian would not use the terms 7 and "mere" in the same phrase.

    I've done 5.5 and it feels like your arms weigh a couple hundred pounds
    each and your face is pulling itself apart.

    Oh, and then chucktard says cars can only corner at 1g. That's even
    funnier.

    <http://www.usatoday.com/sports/2003-02-27-ten-hardest-race-car_x.htm>
    ""Elite drivers will put up with 4 to 5 G's sustained in a corner for
    between five and 15 seconds, ..."
     
    Beauregard T. Shagnasty, Nov 27, 2009
    #20
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