Horizontal motion and vertical motion are effectively independant

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Discussion Overview

The discussion centers on the independence of horizontal and vertical motion, particularly in the context of projectile motion. Participants explore whether this independence can be mathematically or physically proven, and they consider both theoretical and experimental approaches to understanding the concept.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant seeks a mathematical or physical proof of the independence of horizontal and vertical motion, referencing the parabolic trajectory of projectiles as a basis for their inquiry.
  • Another participant suggests that the independence of motion is a postulate and encourages experimentation to validate the concept, implying that theory alone is insufficient.
  • A participant asserts that mathematical proof is possible, indicating that the analysis of vectors can demonstrate the independence of motion components.
  • One contributor explains that the vector representation of motion can be broken into horizontal and vertical components, suggesting that this separation is intuitive but not necessarily understood at a fundamental level.
  • Another participant references Newton's second law (F = ma) to argue that since the x and y components of a vector are independent, this supports the claim of independence in motion.
  • A participant notes that while vertical motion is affected by gravity, horizontal motion remains constant, which they argue serves as evidence for the independence of the two types of motion.

Areas of Agreement / Disagreement

Participants express differing views on the nature of proof regarding the independence of horizontal and vertical motion. While some believe it can be mathematically proven, others consider it a postulate that requires experimental validation. The discussion remains unresolved regarding the adequacy of theoretical versus experimental approaches.

Contextual Notes

Some participants highlight the need for further experimentation to support theoretical claims, indicating that the discussion may be limited by the absence of empirical evidence or consensus on definitions and interpretations of independence in motion.

Cheman
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Is there a way to mathematically or physically prove that horizontal motion and vertical motion are effectively independent? ie - is it possible to derive this fact from, say, vectors?

I know that is is true - the parabola shape of projectiles wouldn't make sense otherwise, but is there a convincing proof for it? It would just allow me to accept this fact if i had a proof, and then i would be happy to use the procedure! :wink:

Thanks in advance. :smile:
 
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When you drop something from a building, does it move eratically all over the place, or does it fall down in a straight line? (assuming nil air resistance)

I think the fact they are independent is just postulate.

To get the proof, do some experimentation.

Everything is only theory until you get down to the lab to check it out.
 
But surely it can be prooved mathematically?
 
it can be prooven mathematically by the analysis of experiments. It seems simple to understand, the vector is bromen up into two compnenets one vertical and the other horizontal. To understand why this happens is like asking why is there inertia. Why do bodies with mass oppose acceleration. Nobody knows, but it's just common sence.
 
Cheman said:
Is there a way to mathematically or physically prove that horizontal motion and vertical motion are effectively independent? ie - is it possible to derive this fact from, say, vectors?


Yes. The motion is determined by Newton II, F = ma, which is a vector equation. Since the two vectors are equal, their individual components must be equal. The x and y components of a vector are completely independent of each other, since the x direction is 90 degrees to the y direction.
 
force is what causes change in velocity, assuming no air resitance... a projectile changes velocity in the vertical direction during its flight... due to gravity. The horizontal however is constant... that proves it right there more or less. The horizontal remains the same regardless of the motion in the vertical direction due to gravity... need more than that?
 

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