Black Sports : Do over head stadium lights contribute to athletes knee injuries?

Discussion in 'Black Sports' started by asmith161718, Jul 29, 2014.

  1. asmith161718

    asmith161718 Well-Known Member MEMBER

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    In this video called How Much Does a Shadow Weight it says that when light hits us from above it actually pushes the body and other objects. According to the video when we are under the sun and our shadow casts we weight more. The amount an object is pushed is very, very small but it's still something that makes me wonder if it has any affect at all? And considering how often that athletes go up and down the field under stadium lights, I can still see it having some kind of affect over time.

     
  2. Dreya

    Dreya Well-Known Member MEMBER

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    hate to do it to you twice in one day but sorry this just aint so.....

    now think about it logicly - which is stronger stadium lights or sunlight - obviously sunlight - soooo if this were true it would be training during the day which would be really bad for you - but to be honest although light does push on you the amount is reduculusly small - it wouldnt be noticable without proper scientific instruments - again think about it - if the effect were really noticeable you should be able to knock over things like playin cards with a laser pen - and ya cant
     
  3. asmith161718

    asmith161718 Well-Known Member MEMBER

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    Maybe. Maybe not. I too agree that it's probable. I chose my words very carefully that's why I said that the chance is very, very small. But according to this article body weight plays a factor in knee injury. So if you are playing for 30 or so minutes in a game and jumping up and down does the act of jumping up and down increase your body weight more? I'm thinking that it just might but I'm not a scientist and my internet searches have came up with zero articles about it.

    http://www.coreperformance.com/knowledge/injury-pain/jumpers-knee.html

    Who’s at Risk
    Jumper’s knee is most common in basketball, volleyball and soccer, which require explosive jumping movements. The condition is also seen in long jumpers and high jumpers, as well as in walkers, figure skaters and mountain climbers. The load placed on the knees is up to 7 times the body weight of a soccer player during the kicking movement and between 9 and 11 times body weight in volleyball when a player lands after a jump.

    Also. Hypothetically speaking I wonder if you place a bouncing ball under sunlight will that ball weight more after each consecutive bounce. The study in the video said Chicago weight 300 pounds more under sunlight but the city of chicago is not bouncing up and down all day. So hypothetically speaking if the city of Chicago bounce up and down will the city weight more after each bounce?
     
  4. asmith161718

    asmith161718 Well-Known Member MEMBER

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    I agree the chance is very, very small but I would if a very very small weight increase could make a different but probably not.
     
  5. Dreya

    Dreya Well-Known Member MEMBER

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    its the jumpin up and down that does it for sure - because of the impact each time - its not just your weight you got to consider but the speed at which your hittin the ground each time.... and when i was saying light pushed on you a very small amount ive not done the actual equations like for a stadium light - but its not gonna be anything more than like a billionth of an ounce or somethin
     
  6. asmith161718

    asmith161718 Well-Known Member MEMBER

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    Gravity affects light and we have to factor in Einstein's theory of general relativity and also that the Human body emits a light source, has a gravitational field and when athletes sweat there clothes are heavier because of the water. There's also a term called Action-at-a-Distance Forces which could also contribute to a knee injury.
    Newton's Laws - Lesson 2 - Force and Its Representation
    The Meaning of Force

    A force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. When the interaction ceases, the two objects no longer experience the force. Forcesonly exist as a result of an interaction.

    Contact versus Action-at-a-Distance Forces
    For simplicity sake, all forces (interactions) between objects can be placed into two broad categories:

    • contact forces, and
    • forces resulting from action-at-a-distance
    Lesson 2 as well as in other lessons.


    http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/961102.html

    Enter Albert Einstein. In 1915 he proposed the theory of general relativity. General relativity explained, in a consistent way, how gravity affects light. We now knew that while photons have no mass, they do possess momentum (so your statement about light not affecting matter is incorrect). We also knew that photons are affected by gravitational fields not because photons have mass, but because gravitational fields (in particular, strong gravitational fields) change the shape of space-time. The photons are responding to the curvature in space-time, not directly to the gravitational field. Space-time is the four-dimensional "space" we live in -- there are 3 spatial dimensions (think of X,Y, and Z) and one time dimension.

    http://gabrielharper.quora.com/In-a-way-were-all-sort-of-eternal
    Your personal field of gravity expands hundreds of trillions of miles into space, and will continue its journey millions of years after you die.

     
  7. asmith161718

    asmith161718 Well-Known Member MEMBER

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    According to this article probably the biggest effect that can influence an object are atmospheric changes.

    http://www.thenakedscientists.com/HTML/questions/question/2288/



    The one that people haven’t written about which is actually quite important for most people and as to do with atmospheric pressure, the atmospheric pressure will change from day-to-day, people know about highs and lows and that the typical change during a night to the high pressure zone move into a low pressure zone might actually change the weight of a person by as much as 6 grams so not 10 or 15 milligrams but 6 grams. Which is the weight of a pencil, for example. And that’s all to do with the buoyancy of the air when the pressure goes up.

    Maybe this is what happened to Lebron James when the air condition blew out during the NBA Finals? Maybe the change of atmosphere contribute to his knee injury.

    Also when a ball bounces up and down continually this happens-

    http://askthephysicist.com/ask_phys_q&a_old5.html

    QUESTION:A ball is thrown straight up into the air and returns to be caught by the thrower. We know that gravity has been acting on the ball the entire time, but the ball has the same kinetic energy when it is caught as when it was released. Can you explain this apparent discrepancy?

    [​IMG]ANSWER: The gravitational force changes kinetic energy, like any force, by doing work on the ball. On the way up the direction and the force are in opposite directions so the work done is negative, W1=-mgh=change in kinetic energy. The kinetic energy started with K and so, when it gets to the top the the kinetic energy is zero. On the way down the direction and the force are in the same directions so the work done is positive, W1=mgh=change in kinetic energy. The kinetic energy started with 0 and so, when it gets to the bottom the the kinetic energy is mgh. So the total change in kinetic energy for the whole trip is -mgh+mgh=0. In a nutshell, the gravity takes away energy for half the trip and adds back that same amount of energy for the second half of the trip.


    So many when an athlete jumps up he feels lighter but when he comes down maybe he doesn't make the necessary adjustments because gravity adds back energy that was lost when he jumped up. And he doesn't make a good adjustment to his knees, ankles when he comes down.



    https://answers.yahoo.com/question/index?qid=20100921041811AAcTkNs

    According to a Q and A on yahoo this is how much gravitational force a 220 pound man pulls. Not sure how accurate it is or how to convert it.

    For example, a person who weighs 220 pounds would have a gravitational pull of approximately 0.0000000006 m/s^2, where something as small as an atom would have a gravitational pull of approximately 0.00000000000000000000000000000000002 m/s^2, then compare that to an object such as Earth which has a gravitational pull of 9.81 m/s^2

    Sports Biomechanics uses the Science of Action-at-a-distance forces to help athletes optimized their performance. I just came across a book called Sports Biomechanic: The Basics: Optimising Human Performance.

    This book uses Newton's laws of physics to improve an athletes movement and performance. I wonder if Pro athletes include biometrics in their training? Probably since they have the best trainers but I doubt this is in the College or High School.

    An excerpt...We apply a force against the ground in running, but the force that propels us, the ground reaction force is directed upwards. This principle is consistent with Newton's a) law of inertia (First Law of Motion) b) Law of Acceleration (Second Law of Motion) C) Law of action-reaction D) Law of Gravitation (Third Law of Motion)
     
  8. Dreya

    Dreya Well-Known Member MEMBER

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    yep i mentioned how gravity effects light by distorting space time in another thread

    key thing though in relation to the original question though is that the effect of light is microscopic - and honestly i dont think the sweaty clothes thing works at all - think about it - where was all the sweat before it was drenchin the clothes??? - it was inside the person - since at least some of it mustve evaporated even if only a small amount the sweaty guy has to weigh less than he did before he started sweatin
     
  9. asmith161718

    asmith161718 Well-Known Member MEMBER

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    Would you happen to know the answer to this question on yahoo Q & A?

    https://answers.yahoo.com/question/index?qid=20131110215052AAbiLkr

    The gravitational force of attraction between
    two students sitting at their desks in physics
    class is 3.75 × 10−8 N.
    If one student has a mass of 41 kg and the
    other has a mass of 55.4 kg, how far apart are
    the students sitting? The universal gravita-
    tional constant is 6.673 × 10−11 N · m2/kg2.
    Answer in units of m



    Whoever asked you this question almost certainly wants the answer provided by "?". Unfortunately, it's wrong. You haven't been provided nearly enough information to answer this. Remember that the universal gravitation formula

    F = G(m1)(m2) / r²

    is true for point masses, and outside spherically symmetric shells. Are your two students point masses or spherically symmetric shells? Of course not.

    What about an approximation? Can your two students be approximated as point masses or spherically symmetric shells? That would be possible if their deviation from being point masses or spherically symmetric shells was "small" compared to the distance between them.

    Personally, with a head, arms and legs, etc., I'd say my deviation from being a point mass or spherically symmetric shell was on the order of 1m. So, is 1m small compared to the the answer provided by "?" No, 1m is not small compared to 2m. If "?" had gotten 100m, I'd say OK. But not 2m.

    To really answer this question, you'd need to know the position density function of each student, and evaluate some horrible integral (you'd almost certainly need to evaluate it numerically).

    Remember that it is not enough to know formulas in physics. You must also know what assumptions were made when they were derived, so you'll know when the formulas can be applied. I really hope that whoever asked you this is wanting you to come back with "this question cannot be answered with the information given", and perhaps with the calculation performed by "?" as proof. If they actually want you to come back with an answer of about 2m, then they should go into another line of work.


    F=G*m1*m2/r²
    or, 3.75*10^-8 = (6.673*10^-11) * 41 * 55.4 / r²
    hence, r²=4.012
    therefore r=2.003 metres
    as simple as that.

    Another good site about Sports Bio-mechanics-

    http://www.humankinetics.com/excerpts/excerpts/basic-mechanical-principles

    The more massive an athlete, the more the athlete’s body mass resists change. A giant 300 lb (136 kg) athlete needs to exert great muscular force to get his body mass moving. Once moving in a particular direction, the athlete must again produce an immense amount of muscular force to stop or change direction. Athletes with less body mass have less inertia and therefore need to apply less force to get themselves going. Likewise, they need less force than a more massive athlete to maneuver or stop themselves once they’re on the move. There are many examples in everyday life of inertia at work. Oil tankers that cross our oceans have tremendous mass and inertia. They need powerful engines to get them going and huge distances to stop and to turn around. Consider Japanese sumo wrestlers or defensive and offensive linemen in American football. Just like the oil tanker, these athletes must apply tremendous force to get their body mass moving and then apply a huge amount of force to change direction or to maneuver the great masses of their opponents.
     
  10. Enki

    Enki The Evolved Amphibian STAFF

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    Have you ever heard of a force called gravity? It is always on, and HID lights has nothing to do with this force that is pulling a mass downward. Here is the calc....w-mg.

    Now nowhere in there is the variable for the speed of light. If it were, our weight would be off the charts.

    Peace!
     
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