Firecracker Physics: Exploding Directionality

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Discussion Overview

The discussion centers around the explosive behavior of firecrackers, specifically regarding the directionality of the explosion. Participants explore whether the explosion is omnidirectional or favors specific directions based on the orientation of the firecracker, particularly in relation to its ends and sides.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about the explosion characteristics of firecrackers, questioning whether the explosion is omnidirectional or if it favors the ends of the cardboard tube.
  • Another participant suggests that the explosion would be more effective if the firecracker is positioned lengthwise, referencing shaped charges as a related concept.
  • A later reply supports the idea that more explosive force may emerge from the ends of the cylinder, indicating that expanding gases would likely follow that path.
  • However, a different participant challenges this view by noting that firecrackers often split at the middle when exploded, suggesting that directing one of its poles at a target may not yield the expected results.

Areas of Agreement / Disagreement

Participants express differing views on the directionality of the explosion, with no consensus reached on whether the ends or sides of the firecracker produce more force upon detonation.

Contextual Notes

Participants reference concepts such as shaped charges and the physical behavior of exploded firecrackers, but the discussion lacks detailed analysis of the underlying physics or specific experimental evidence.

wil3
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Hello, this question may not be appropriate for this forum, but I feel that chemistry people are more likely to understand the basic operational characteristics of firecrackers.

Say I have a standard obnoxious firecracker, like the ones that they sell connected in strings for your neighbors to detonate early in the morning. The firecracker is just a bunch of black powder in a cardboard tube, and the tube explodes when the fire reaches it.

My question is how the tube explodes. Is the explosion somewhat omnidirectional, or does it favor the poles of the cardboard tube? By that I mean, if I were trying to pry open a door or something (not that I am, this is just to illustrate), would more force be directed onto the two surfaces if the firecracker was inserted lengthwise or on its end?
 
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Lengthwise.

Look up shaped charges. Firecrackers aren't that sophisticated but it's still interesting.

Don't try to make one. You get a horrible injury to yourself or someone else. It's not fun.
 
I assure you that I'm not planning on it :P

So by lengthwise you mean with its ends touching the two surfaces? As in, more explosive force comes out of the poles of the cylinder? That makes sense to me, because that's the way the expanding gases are more likely to go, but I thought I should check. Thank you very much.
 
if you look up at a blown up firecracker (the "blackjack"/on a string type) you will find they split at the middle, leaving the two ends more or less intact

so i don't think you would get more mileage out of one by directing one of its poles at your target