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Thread: What causes inertia?

  1. #1 What causes inertia? 
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    I am looking for opinions on the cause of inertia.

    Is it caused by other mass in the universe?

    Is it a property it derives from within itself?

    Is there a time delay before it starts?

    Does it last for a time after acceleration stops?

    It could be the result of a mass being removed from its own gravitational field.

    You may comment on the above or suggest some ideas of your own.


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  3. #2  
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    I'd say it's part of Mass/Matter's propensity toward not changing.

    Objects which are not moving, cannot start moving without an energy expenditure.

    Everything in space "is" moving. however relitave to itself, nothing is moving.

    Nothing to do with Gravity, Electromagnetism, or any other kind of energy. It is simply Equilibrium in action. Things need energy for them to change their momentum. Inertia is the inherent reason for this.


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  4. #3  
    Forum Ph.D. william's Avatar
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    You might find "Mach's principle" of interest...
    http://en.wikipedia.org/wiki/Mach's_principle

    cheers
    "... the polhode rolls without slipping on the herpolhode lying in the invariable plane."
    ~Footnote in Goldstein's Mechanics, 3rd ed. p. 202
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  5. #4 internal or external? 
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    To say something is moving you need an outside reference so I am assuming you are saying inertia is not totally an internal property.

    You said “relative to itself nothing is moving.”
    By this I would take you to mean that the internal particle motion average momentum is zero, and not that it has no motion.

    If you intended to suggest that inertia is totally and internal property please correct me.
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  6. #5 For william 
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    Einstein’s definition of mach principal was “perception is relative” while Mach himself seemed to be of the opinion that reality is relative.

    A subtle difference but Mach was not able to come up with equations that predict physical events where Einstein was.

    So if the universe spun and you remained stationary would you experience centrifugal acceleration?
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  7. #6  
    Forum Senior anand_kapadia's Avatar
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    Every particle whether it be an atom or the whole universe tries to be in the rest position. It is where inertia applies.
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  8. #7 Rest position is relitive. 
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    Rest position is relitive.

    Two masses are moving with respect to each other.

    They are both at rest.
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    If all the masses requirement for existing is that it is still relative to itself, how come it can't move differently relative to others ie. what forbids it, the existence of a medium no matter how basic?
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  10. #9 A real mind bender. 
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    Mass can not move with respect to another mass faster then the speed of light because a gravitational force develops between the masses preventing it.

    At lesser speeds it is less prevalent but it still exists however small it may be.

    The masses do not move independently.

    Space time variation is a fancy way of saying energy wave however big you may envision it to be.

    So something conveys at least information between bodies of mass.

    Call it what you will, but it exists.

    The properties aether may not be what we are used to dealing with.

    If it is composed of energy waves then no matter how you measure them they will always render a speed of light velocity.

    This would render a medium with motion of the speed of light in all directions at once which could be considered equivalent to a zero composite velocity.
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  11. #10  
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    Quote Originally Posted by anand_kapadia
    Every particle whether it be an atom or the whole universe tries to be in the rest position. It is where inertia applies.
    That is not entirely true. If it is in the rest position already, then yes it likes to stay that way. However if a force acts upon it and gets it moving then it will carry on moving at the same speed and in the same direction until another force changes its momentum.
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  12. #11  
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    Please visit here for your answer..
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  13. #12  
    Forum Senior anand_kapadia's Avatar
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    Leophkins said:-

    That is not entirely true. If it is in the rest position already, then yes it likes to stay that way. However if a force acts upon it and gets it moving then it will carry on moving at the same speed and in the same direction until another force changes its momentum.[/quote]

    Yes i forgot to write uniform motion. This condition applies to either rest or uniform motion.
    Thanks for correction
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  14. #13  
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    Inertia is a phenomina of the universe we find ouselves locked in.

    Well that's the engineers view, we can calulate it, there are laws we apply which predict it. The engineer will tell you also it is the 'effort' required to 'get things moving'. I cannot see our universe would 'work' or be viable without it, as that would imply no movement possible therefore no 'time' or that no effort was required to move things therefore they might never 'stick together' at an atomic level but just 'float' around, no force for movement and therefore IMO no gravity.

    You might consider therefore tying inertia to that force which prevents atoms from occupying the same space, in that I do not fall through the earth as atoms appear to 'resist' each other at that scale.
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  15. #14 Stopping 
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    When im in a car, train, bus etc and the vehicle comes to a complete stop, I can sometimes feel myself being pulled back ever so slightly in the opposite direction to the initial motion. Why is this ?
    The hand of time rested on the half-hour mark, and all along that old front line of the English there came a whistling and a crying. The men of the first wave climbed up the parapets, in tumult, darkness, and the presence of death, and having done with all pleasant things, advanced across No Man's Land to begin the Battle of the Somme. - Poet John Masefield.

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  16. #15  
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    because you arn't actually connected to the friction being generated by the trains wheels as it slows, you're body is trying to travel at the speed of the train before breaking, so you in effect carry on moving for a short while, whilst the train is slowing
    Come see some of my art work at http://nevyn-pendragon.deviantart.com/
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  17. #16 Re: Stopping 
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    Quote Originally Posted by leohopkins
    When im in a car, train, bus etc and the vehicle comes to a complete stop, I can sometimes feel myself being pulled back ever so slightly in the opposite direction to the initial motion. Why is this ?
    This is because when the car is moving your whole body is in the inertia of motion. Then if the car suddenly stops your lower portion of the body to which was aligned with the car comes to rest with car but the upper portion being in inertia of motion tries to be in motion and you get a forward bump.
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  18. #17  
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    It is actually because the muscles of your body are compensating for the decceleration of the vehicle, that is you are leaning back (if facing forward). the pressure you apply to lean back exactly compensates the decceleration trying to make you lean forward, the resulting balance keeps you upright .When the vehicle stops, one of the forces balancing your body [the decelarion] dissappears ,it catches you 'off gaurd' and you begin to fall back as you were leaning that way.
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  19. #18  
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    due to the motion and force, some amount of energy is acquired in the object and its mass atso contributes to inertia.
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  20. #19  
    Forum Ph.D. Steve Miller's Avatar
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    http://en.wikipedia.org/wiki/Inertia

    and

    I'm a bit puzzled about your question indeed. Since earth moves steadily a object in rest obviously,
    isn't but truly. The object has got all the motion earth even has got. As you would start to move
    this particular object you would influence a previously to the object given motion. Inertia was not of
    flamboyant interest at this moment, I would think.

    As you, lets assume we are in space cause there was no other place we would know of today, will
    move an object there, where the known motion of earth was not effecting the object, further away from
    earth not even secondarily, if the object was inert there, there must be something hemming the objects
    move.

    That would mean inertia was set off by the objects surroundings, more or less interactive with the
    object.

    Primarily, I assume inertia may not be triggered from the object but its surroundings.

    Steve
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