Newton's First Law Does not make sense

Discussion in 'Physics & Math' started by OPC51, Feb 6, 2003.

  1. everneo Re-searcher Registered Senior Member

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    OPC51 :

    The ball did acquire momentum so did you and your car.
    Unless it is nullified the ball will come with you (in hand , in air, in pocket etc ) if you travel straight.
     
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  3. Prosoothus Registered Senior Member

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    chroot,

    I'm attempting to unite inertia and the reason that light travels at c, in the same model. I believe that there is a relation between the two, and I don't consider inertia or the speed of light so fundamental that I can't ask "why?".

    You know, chroot, many of our debates come down to you believing that a property of matter/energy/space is fundamental, while I do not. How exactly do you determine if a property is fundamental or not??

    Tom
     
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  5. chroot Crackpot killer Registered Senior Member

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    Experiment.

    So could you answer my questions? Do you or do you not agree that your model has just as many (or more) axioms as mainstream science?

    Why does acceleration warp space?
    Why does it take less energy for the space to stay warped?


    - Warren
     
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  7. Prosoothus Registered Senior Member

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    chroot,

    That's not good enough. Let's say you lived ten thousand years ago, and you dropped a rock on your foot. Using your math skills (which were very impressive for those days), you calculated that the rock fell at 10 m/s/s.

    After this amazing discovery, you go run and tell your neighbor (who also lives in a cave

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    ) Your neighbor asks you, "Why does the rock fall at 10/m/s/s?". You tell him that he shouldn't ask such fundamental questions. After all, everyone knows that 10 m/s/s is a fundamental physical constant throughout the universe. Well, at least all your experiments show that it is.

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    Yep, you're right. But I am attempting to explain two phenomenas using one model. So it would only be fair to divide the total number of axioms in my model, by two.

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    I don't know. I'm still working on it.

    Tom
     
  8. chroot Crackpot killer Registered Senior Member

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    That's a valid point -- but it's not a fair representation of science. You must assume that there are fundamental things in nature -- fundamental physical laws, fundamental particles, and so on. The task is then to isolate which rules, interactions, and particles are truly fundamental. This task never stops. The scientist drops the brick, and establishes an experimental basis for what he believes is a fundamental rule: that the brick falls with 10 m/s on the surface of the earth. But he has to continue to check that fundamental rule forever -- even one discrepancy means it's not fundamental. So he goes around, dropping the brick from tall mountains... and realizes it's not the same on top of the mountain. His rule is not really fundamental at all.

    Scientists are now working on experiments to test the fundamentality of general relativity -- subtle experiments like frame dragging, for example. The scientist is NEVER sure that his model is accurate, even when every experiment he is capable of doing says it is. As soon as he becomes technologically capable of doing another experiment, he must do that one, too. There is no way to prove that GR is right; only ways to prove it is wrong.
    Then please refrain from putting down mainstream science because it is incapable of explaining "why" things happen -- you can't either, even in your own model.

    - Warren
     
  9. Prosoothus Registered Senior Member

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    chroot,

    Exactly. I agree 100%. That's why we should never stop asking the question "why?". What would happen if something that we all assume is fundamental, really isn't? Our own assumptions would prevent us from ever finding out if it really is fundamental.

    Tom
     
  10. chroot Crackpot killer Registered Senior Member

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    What on earth would lead you to believe that I don't question things? What makes you think that I, or any other scientists isn't skeptical? The bottom line, Tom, is that you don't know any real scientists. Your opinion that scientists are dogmatic establishmentarianists is not very well supported at all. You're missing the point that the reason that most scientists became scientists was because they are skeptical and question things. They want to learn the theories inside and out specifically because they do not trust them! There are open questions in relativity theory -- boatloads of them! -- but some parts of the theory, like time dilation, gravitational time dilation, and so on (the parts you question in your typical half-logical fashion) have been tested to the fullest capability of man's current technological abilities. We have no reason to believe those parts of the theory are incorrect at the current time. As technology develops, you can bet your ass that scientists will make use of it to verify again and again that our understanding is correct.

    - Warren
     
  11. Prosoothus Registered Senior Member

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    chroot,

    When I asked, on another thread, why time dilation and length contraction occur at relativistic speeds, what was I told?? Was I told that it's unknown, but your working on it? No, I was basically told that time dilation and length contraction are so fundamental that I shouldn't ask "why?". What if they are not fundamental (if they even exist)? What if the mechanics behind these phenomena are so important that understanding them would give us a better understanding of how the universe works? By not asking "why" about everything and anything, aren't we putting up roadblocks on the path leading to the theory of everything?

    Tom
     
  12. chroot Crackpot killer Registered Senior Member

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    I'd agree with that. On the other extreme, if we refuse to dismiss theories which are not useful (like yours), we'll be putting up roadblocks too.

    - Warren
     
  13. §lîñk€¥™ Uneducated smart alec Registered Senior Member

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    They'd probably read some of your other posts and considered that it would be a waste of time.
     
  14. Prosoothus Registered Senior Member

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    §lîñk€¥™,

    Well, look who's back. It's chroot Jr.....
     
  15. §lîñk€¥™ Uneducated smart alec Registered Senior Member

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    I'll take that as a compliment, even if Warren might not (high fives Warren

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    ).

    kind regards
    Paul aka §lîñk€¥™
     
  16. 1119 Registered Senior Member

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    Prosoothus may be THE crackpot of this site but his constant challenging of Relativity never fail to provoke answers from the bright minds of this site. As someone who follows the exchanges in these threads, it is always a learning experience for myself and that is the prime reason why I joined sciforums.

    I always look forward to Prosoothus' threads not so much for his theories but for the rebuttal or answers they are likely to provoke from the scientists of this site.

    For that, I think Prosoothus deserve at least some courtesy if not respect, especially from junior and learning members, such as myself.

    Just my two cents....
     
  17. James R Just this guy, you know? Staff Member

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    39,397
    OPC51:

    Consider your ball in the car example.

    When you're holding the ball in your hand, the forces acting on the ball are:

    * gravity (downwards)
    * normal reaction of hand (upwards)

    That's all. There is no "force of the engine" on the ball, provided the car is travelling at constant speed along the road. Note, however, that the car has two extra forces to keep it travelling at constant speed - the engine force and the friction forces of the road and air.

    There is no net force on the ball, so it doesn't accelerate.

    Now, consider the ball when it is in the air after you've thrown it. Now, there is no normal reaction force. The only force remaining is gravity, acting downwards. Therefore, the ball continually accelerates downwards until it lands back in your hand again.

    Newton I says if there's no net force, there's no acceleration. There is no problem with that law in this example.

    Hope this helps.
     
  18. Crisp Gone 4ever Registered Senior Member

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    Science philosophy to the rescue.

    Hi,

    As an addition to James' post; you might wonder why Newton's first law exists in the first place.

    If you assume the existance of an object such as a "force" and that this "force" can give rise to an acceleration according to F = ma, then Newton's first law *must* but true.

    If there is no force acting on an object, then F = 0 -> a = 0, or the change in velocity is zero (i.e. its length, the speed doesn't change and its direction does not change).

    Why is the force (or rather: the component along the direction of motion of the car) zero ? ---> See James' post

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    Cheers,

    Crisp
     
  19. OPC51 Registered Member

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    Thanks

    Thank you all,

    I have clarified my thoughts somewhat now. I have realised that there was a mistake in my reasoning but I actually was onto something.

    It turns out that Newtons First Law does sometimes appear to be wrong. It turn out that newtons first law will only work for inerita frames not for all arbitary observers. ( I will be digesting this one a bit longer, realtivity is still newish to me!)

    I accept the point about F=ma. I was thinking about using this to derive a algaberic equation that could be integrated to get velocity components. The problem I had was that with no horizontal motion in the 2nd forces model I could not see how it would all stack up when I integrated it down to an expression for velocity.

    My approach was wrong. What I should have done is to simpilfy it and assume a standard configuration for the frame of references. The observer in a stationery frame and the car as the other frame.

    For me this makes momentumn more meaning full. Momentumn is normally explained has a number that represents a physical characteristic of the object. From now I will think of momentumn as the thing that keeps the frame with the car moving, I will imagine a little arrow point in the direction that the frame moves with constant speed.

    There are other questions, but I'll post them under a different topic once I have though about them a bit more.

    Thank you all.
     
  20. Prosoothus Registered Senior Member

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    1119,

    I'll try to take that as a compliment.

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    Tom
     
  21. everneo Re-searcher Registered Senior Member

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    U are an optimist Tom..! Keep going on.. Warren will follow suit..!

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  22. RDT2 Registered Senior Member

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    quote:
    --------------------------------------------------------------------------------
    I always look forward to Prosoothus' threads not so much for his theories but for the rebuttal or answers they are likely to provoke from the scientists of this site.

    For that, I think Prosoothus deserve at least some courtesy if not respect, especially from junior and learning members, such as myself.
    --------------------------------------------------------------------------------

    Courtesy is no problem - provided it's reciprocal - and we can all learn from each other. The problem is that Pros' 'theories' are often not backed up by experimental evidence - which is, no matter what you may hear - the final arbiter. And just to play the 'elder statesman', remember that the net is not refereed - if you want the authoritative view on any topic, you must read the scientific literature.

    Cheers,

    Ron.
     
  23. Prosoothus Registered Senior Member

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    RDT2,

    Maybe when you have a theory, you can run into your basement and test it in your fancy physics lab, or in your own personal particle accelerator.

    Unfortunatley, I don't have the equipment or money to experimentally test my theories. The only thing I can do is to share my theories with other people and hope that it reaches someone who does have the money and the equipment to test them (or someone who can prove that they are wrong).

    Tom
     

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