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Everything posted by Ghideon

  1. Then point out the specifics. Trying to describe your fictive scenarios using words opens for mistakes: and Is not the best way to do physics. It would be easier to do a mathematical analysis using a proper model.
  2. The center of rotation, when man is trying to swing the string + ball around in space, will be somewhere along the string, depening on the mass ratio man vs ball. When ball moves radially for a short while the man moves in the other direction for a short while. On earth we neglect these effects since earth is massive, we consider the earth to be stationary and the man able to hold his position. For a massive ball, such as in hammer throw, the effect on the mans position can't be neglected on earth or in space. Slightly off topic comparison: The effect on earth is not as easily neglected if we would look at the system earth + moon I have told you what is happening in mainstream physics. You are moving the goal posts by switching frame of reference, location to zero g and now hammer instead of low mass ball. Please get to the point.
  3. Nothing new*, rotation will continue unhindered as long as there is no further change introduced. In outer space the analysis need to be different. I was assuming (maybe wrongly) that his was taking place on Earth: It is not easy to try in outer space. But simply put, angular momentum is conserved. *)The man getting tired is one possibility in reality
  4. You said that but it does not seem to be correct. In a rotating frame of reference there is always centrifugal force* unless angular velocity is zero. step 1) centrifugal force and centripetal force are in balance step 2) 2.1) the centrifugal force is, for a short time, greater than the centripetal force 2.2) the centripetal force will increase and be greater in magnitude than centrifugal force for a short while step 3) centrifugal force and centripetal force are in balance and have a greater magnitude than in step 1. NOTE: again this only applies when analysing the motion from the rotating frame of reference, rotating with the man along the same axis. From a stationary observer beside the man there are no centrifugal forces, they are fictitious. This is important. Failing to realise the importance of this leads to wrong conclusions. *) To be more precise; Inertial centrifugal force. Reactive centrifugal force is not needed to include at this time.
  5. Ok, we are in a rotating frame of reference where fictitious forces may apply. Why is there a centrifugal force only in step 2? There is no point in analysing this slightly more complicated example until there is some common baseline regarding the basics.
  6. In what frame of reference are you doing the analysis? (You do know what a frame of reference is?) Are we looking at the man from a stationary position beside him or are we rotating along with the man so that the string is attached in origo and the ball appears at rest when angular velocity is constant? Why is there a centrifugal force only in step 2?
  7. Ok. That can be fixed. I do know about gravity and heliocentrism, I'm just looking for a way to explain it in accordance to your current level of knowledge and interest in the subject.
  8. Incorrect. Please start a thread in speculations and propose a model and supporting evidence. The question does not apply since you were incorrect in the first question in the post.
  9. In what frame of reference are you doing the analysis? Why is there a centrifugal force only in step 2? Are you using different frames of reference in steps 1 and 3?
  10. It's more complicated than you realise or at least more complicated than you describe. 1) Probably correct in ideal situation 2) not necessarily, If you just rotate faster then the rope and the ball will lag behind and curl around your hand. If the rope is free to move without your hand getting in the way (rope already almost parallel to the ground for instance) you need to analyse the difference in velocity. Increasing the rotation too fast gets you out of the rhythm and the ball may stop rotating. I have of course rotated a ball on a string faster and faster. That can be achieved by pulling the rope slightly harder while at the same time increasing the angular velocity to compensate. Turning to speed up a rotating ball by just rotating faster may or may not work. Compare a contemporary hammer throw (ball on string) vs Scottish hammer throw (ball on a shaft). If we change the laws of physics then things will change. Other than that, hard to tell. What are you trying to achieve by analysing non-physical situations? Why the focus on things that can't happen, and can't be correctly described within the laws you try to apply?
  11. If we assume you are discussing science then your question needs to be reformulated.
  12. Ok It depends, an almost rigid wire behaves different than a rubber band for instance. It also greatly depends on how much the speed is increased. The non-rigid rope may stretch and the tension in the rope may increase while I try to spin faster. The rope may coil around my hand for some part of a lap. It may take some time (some number of rotations) before the system is stable again. A lot more details are probably needed to make a prediction. Why such a complicated example?
  13. Sorry, Im not following. Above my post is: You asked me about a ball on a non-rigid rope. I'm trying to read: Please clarify.
  14. Gravity can be used to model and predict how the celestial bodies move in the solar system. Off topic. And already covered in my foot note.
  15. or Classical mechanics does not correctly describe he internals of an atom and hence scientists are using other models. You are using an invalid approach and your results does not match experiments, observations and theoretical predictions.
  16. It is a bad use of words, by me. Maybe better: fictitious force in a linear accelerating frame of reference (as compared to Euler and Centrifugal forces in rotating frames of reference)
  17. Thanks. I try to figure out if the problem is understanding acceleration and fictitious forces in general or if the misunderstanding is isolated to circular motion. I'll try to post some examples of circular motion later.
  18. But it is still about circumventing Newton? You said: Linear fictitious forces can't help us circumvent Newton but Centrifugal or Euler forces can, according to you?
  19. Satellites sent to remote areas in solar system (and beyond) are not affected by any aether. Satellites maintain constant velocity* *) Not including possible solar wind interaction and gravitational slingshot manoeuvres etc
  20. Your assumption is incorrect. Why circular and not linear? Why, according to your incorrect physics, are circular motion special? Understanding how you believe that may help writing a good explanation. No. (Hint: using an atomic model (that have been superseded by newer models) gives you incorrect predictions when applying the model where it is not applicable. Same mistake as when trying to use Newtonian physics for photons or for relative velocities close to the speed of light, c.)
  21. I agree. Good list of special characters. Just an additional note @zak100: You never told us what you or your teacher uses so you need to be aware that in some cases the escaping differs among regular expression styles. Some platforms use backslash to escape parenthesis: \(regexp\).
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