What Angle and Point Ensure a Small Disc Hits a Quadrangle Board Predictably?

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Discussion Overview

The discussion revolves around the problem of predicting the trajectory of a small disc hitting the walls of a quadrangle board. Participants explore whether a general formula can be established to determine the angle and point of impact after multiple collisions, considering both deterministic and potentially irregular outcomes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that it is possible to calculate the trajectory of the disc for each collision, questioning if a general formula exists for predicting the angle after n hits.
  • Another participant asserts that while individual collisions can be calculated, a general formula is not feasible due to the need to account for the specific borders of the quadrangle after each hit.
  • A later reply indicates that for specific shapes like rectangles or certain triangles, a general formula may be applicable, but not for arbitrary quadrangles.
  • One participant raises the idea that if the hits are irregular, it might seem random, but clarifies that the process is deterministic, influenced by the previous hit's position.
  • Another participant agrees that the system is deterministic and notes that it shares some properties with chaotic systems, though it is not chaotic in the mathematical sense.

Areas of Agreement / Disagreement

Participants generally agree that individual collisions can be calculated, but there is disagreement on the existence of a general formula for arbitrary quadrangles. The discussion remains unresolved regarding the predictability of hits on irregular shapes.

Contextual Notes

Limitations include the dependence on the specific geometry of the quadrangle and the potential for rounding errors in calculations after multiple hits. The discussion does not resolve the implications of irregular shapes on predictability.

rajeshmarndi
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If we hit this quadrangle board(see the attachment) with a small disc on one of its wall, at a certain point with a certain angle, it will hit the four wall many times.

Can we determine at what angle and at what point, the small disc will hit on the wall after n hit on the wall.

That is, can it have a formula?

Also when a computer shows the result, does it calculate for each hit on the wall and then reach, where the final hit will be.

Thanks.
 

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You can calculate each individual collision, sure. Do that n times for the result. Due to rounding errors, the prediction will become bad if n is too large.
 
mfb said:
You can calculate each individual collision, sure. Do that n times for the result.
I mean, can there be a general formula, that can determine the angle where it will hit after n collision.
 
Not in general, as you have to calculate the correct border every time. For special cases (like rectangles, some triangles and so on), yes there is.
 
Does this mean, for a specific side a,b,c,d(except special cases you mentioned which are symmetry) the hit on the wall, will be said to be irregular. If irregular, then isn't it become random?

I know it cannot be said to be random, as the hit depend upon the position where the previous hit was. It is just that, it cannot be determined through a general formula. If I'm right, just like the generation of Prime numbers.
 
It is deterministic, not random. It is not even chaotic in the mathematical way, but it certainly shares some properties with chaotic systems.
 

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