Cube Projectile Motion: Air Resistance & Cross Sectional Area

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Discussion Overview

The discussion revolves around the projectile motion of a solid cube launched at an angle, specifically examining the effects of air resistance on its orientation and the determination of its cross-sectional area during flight. The conversation touches on theoretical aspects, practical implications, and challenges in predicting the cube's behavior in a dynamic fluid medium.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether the cube would change its orientation while flying, given that two of its faces are perpendicular to the initial velocity vector, and seeks to understand how to find the cross-sectional area at any moment.
  • Another participant challenges the clarity of the initial question, suggesting a need for rephrasing to better convey the intended meaning.
  • A different participant expresses skepticism about the ability to predict the cube's orientation during flight, citing the complexity of the variables involved and the need for advanced tracking technology.
  • Concerns are raised regarding the design of the cube as a projectile, highlighting its potential instability and the challenges in achieving spin stabilization.
  • Vortex shedding is mentioned as a relevant phenomenon that could impact the cube's flight, with a link provided for further exploration of the topic.
  • One participant reflects on the unpredictability of the cube's orientation, suggesting that the multitude of variables makes accurate predictions unlikely.
  • A humorous analogy is made comparing the unpredictability of the cube's flight to predicting the behavior of a person in a tornado while hang-gliding.

Areas of Agreement / Disagreement

Participants express varying degrees of skepticism about the ability to predict the orientation of the cube during flight, with no consensus reached on the feasibility of such predictions or the implications of air resistance on its motion.

Contextual Notes

The discussion highlights limitations in the ability to model the cube's behavior due to the dynamic nature of air as a fluid medium and the numerous variables that influence projectile motion.

Mike Jones
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We have a solid cube with some mass that we fire as a projectile at some angle. The cube is launched in such a way that two of the faces are perpendicular to the initial velocity vector. Assuming there is air resistance, would the cube change its orientation while it flies, even if the mass is balanced throughout the cube? If not, how can we find the cross sectional area at any given time?
 
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If two planes are each perpendicular to a specified vector, they are either the same plane or they are parallel to each other.

I don't think you said what you meant. Would you try again, please?
 
I can't answer your last question; in fact, I doubt that it can be answered. You'd have to have multiple laser scanners tracking the thing constantly.
I will say, just in case your basic goal is weapons development (either real or fictional), that what you've described is one of the worst possible designs for a firearms projectile. Beside its inherent instability, you can't effectively impart the twist that goes into spin-stabilizing a real bullet. Outside of any man-made considerations, remember that air is a dynamic fluid medium, not a constant. A 1 km/hr change in wind speed can throw something off target by a huge amount.
 
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That's an excellent link, 256bits, with lots of really nice secondary links.
 
Basically, I'm wondering if it's possible to predict the orientation of a cube as it flies through the air. Based on the responses, it seems as though there are too many variables for such as predictive function to exist without producing inaccurate results.

Thank you for the link though! Very cool.
 
Mike Jones said:
Based on the responses, it seems as though there are too many variables for such as predictive function
I'm guessing that it would be about the same as sending someone into a tornado in a hang-glider and trying to predict where he'll puke.
 

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