# Atmospheric Pressure Demonstrated With Bruce Yeany

Submitted by: Essen 2 months ago in
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Sadly for future students, Mr. Yeany is retiring this year, but his science lessons live on.
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Is he really a Science teacher? It is the same principal as a sharp knife vs a dull knife interact with opposing forces. As pressures increase with equal force behind the enforced pressures increase as the area of application diminishes. If he is that dumb he needs to step down.
Male 1,791
@_flung Its not so easy as just application of force.  you could argue that the energy of the hit is being absorbed by a smaller cross section of wood, therefore the smaller pieces should break easier.  This would be true if the resisting force is sufficient for both pieces.

he demonstrated 1) air pressure of the atmosphere is involved 2) the amount of wood on the desk makes a difference. 3) large pieces still work even if the piece is shorter overall

Is it just air pressure pressing down on the wood area?  if that was the case, 15 psi over the entire area of even the smaller stick would be sufficient to hold it down to permit breakage.

the paper is the key here.  It is slowing air from getting under the board when struck.  obviously the wider boards have more surface area farther in from the board's edges and so the resultant air pressure force delta (when lifting) is much larger.

Only further experimentation will show the relationship between absolute area, proportions of the wood on vs off the desk, and length:width radio.

It is an excellent experiment for showing 1) simply behaviors have complex mechanisms behind them 2) "common sense" answers have a kernel of truth, but are not he whole truth 3) systemic and rigorous examination of all the variables is the only way to get to the root causes
Male 1,791
punko try this at home, if you have flat, smooth wood.  Take the small piece and place it on a shallow puddle of water on the desk.  You'll find the small pieces break without any mass on top, as the water really slows the introduction of air under the board.
Male 1,859
Very good! I like this.
Male 13,197
Deleted: Off topic

Fancy
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