Surprising Physics: Falling Flat Boards & Chimneys

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    Falling Flat Physics
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Discussion Overview

The discussion revolves around the surprising physics of falling objects, specifically a flat board and a chimney, and the unexpected behavior observed when they break upon impact. Participants explore the mechanics of rotation and acceleration in the case of the board, while also discussing the breaking patterns of chalk and chimneys when dropped. The conversation touches on concepts of torque, moment of inertia, and the nature of brittle materials.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the mechanics of a flat board falling off a table, calculating its angular acceleration and suggesting it accelerates faster than freefall due to the normal force at the loose end.
  • Another participant introduces the idea that a falling chimney breaks into approximately π pieces, which sparks confusion and debate about the validity of this claim.
  • Some participants challenge the notion of breaking into an irrational number of pieces, questioning how a physical object can be said to break into π pieces.
  • One participant shares personal experience with dropping chalk, claiming it consistently breaks into three large pieces and several smaller fragments, approximating π pieces, which others find dubious.
  • There is a discussion about the differences in failure mechanisms between chalk and chimneys, with some arguing they are unrelated while others suggest there may be some connection.
  • Concerns are raised about the impact conditions, such as height and type of chalk, affecting the breaking pattern, leading to further questions about the nature of the observations made.

Areas of Agreement / Disagreement

Participants express a range of views, with no consensus on the relationship between the breaking patterns of chalk and chimneys. Some agree on the mechanics of the board's fall, while others dispute the claims regarding the number of pieces chalk breaks into and the relevance of the chimney example.

Contextual Notes

Participants note that the observations about chalk breaking may depend on specific conditions such as the type of chalk and the height from which it is dropped. There is also uncertainty regarding the definitions of "pieces" and how they relate to the approximation of π.

  • #61
honestrosewater said:
Do yours carry brooms?

Sure. They use them to keep the storm drains clear.
 
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  • #62
Integral said:
As I write, I notice that something strange is happening outside, there is some unusual form of energy pouring through my windows, and the clouds all seem to be blue?
Janus, what is that big yellow thing in the sky?

I don't know, But I bet you is has sumptin' to do with one of dem der' "dry spells" cast by a "sand witch".
 
  • #63
Janus said:
I don't know, But I bet you is has sumptin' to do with one of dem der' "dry spells" cast by a "sand witch".
That sounds reasonable... Now I am hungry! A sandwitch and some round \pi sounds real good.
 
  • #64
Integral said:
That sounds reasonable... Now I am hungry! A sandwitch and some round \pi sounds real good.

Round \pi? I thought \pi r^2?
 
  • #65
Janus said:
Round \pi? I thought \pi r^2?
That is a common myth. When was the last time you ate a square \pi?
 
  • #66
Integral said:
That is a common myth. When was the last time you ate a square \pi?

It was a Shepherd's \pi.
 
  • #67
I like to fit square \pi into a square meal; It's more efficient that way.
 
  • #68
This chalk business is reminiscient of Feynman's conjecture: If you grasp the two ends of a dry spaghetti noodle and break the noodle by bending, it is almost impossible to break it into any less then 3 pieces.
 
  • #69
Integral said:
That is a common myth. When was the last time you ate a square \pi?

I usually encounter it in a triangular prism form.

http://www.rockfield.co.uk/images/chimney_collapsing_real.gif
This chimney broke into \pi pieces.

So tomorrow I'll settle this - if I remember to buy chalk. I'll try and get the sidewalk form as well. I don't have a highspeed camera.
 
Last edited by a moderator:
  • #70
I bought the chalk today, but I'm going to do it tomorrow. I'm confident it will break into pi pieces. Happy trails!

-Mr. Smith
 
  • #71
Mk said:
I bought the chalk today, but I'm going to do it tomorrow. I'm confident it will break into pi pieces. Happy trails!

-Mr. Smith
Watch out for the witches and shepherds.
 
  • #72
Now he even has me waiting for his results :smile:
 
  • #73
... he better come up with a detailed report ... gotten to the point that have to make someone do a lab assignment (for real) about this topic :biggrin: .
 
  • #74
I forgot to do it! Oh no, its 11 o'clock, I will do it tomorrow.
 
  • #75
So with my box of 16 3 and 1/4 inch, long-lasting non-toxic plain RoseArt white chalk, I would have to conclude: Myth busted.

Four trials, at 3 heights: 36", 42", and 48" inches.

At 36 inches:
Trial 1: 2 pieces (1:1)
Trial 2: 2 pieces (2:1)
Trial 3: 4 pieces (1:1:1:1)
Trial 4: 1 pieces

At 42 inches:
Trial 1: 2 pieces (1.5:1)
Trial 2: 1 pieces
Trial 3: 1 pieces
Trial 4: 3 pieces (1:4:1)

At 42 inches:
Trial 1: 2 pieces (2:1)
Trial 2: 2 pieces (1:1)
Trial 3: 1 pieces
Trial 4: 3 pieces (4:1:4)

Not one time did the chalk break into pi pieces.

Sorry kids.
 
  • #76
No wonder - you got long-lasting chalk! :eek:
 
  • #77
... now for starters someone fit a Weibull distribution to the results please :biggrin: ... we'll see what kind of brittle material we're talking about.
 

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