Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Chemistry4me on 10/01/2009 11:12:13
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Why are raw eggs easier to crush on their side compared to standing up straight? [:-\] [:-\]
What do you think? [8)]
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When you're applying force to the ends, the force is distributed more evenly over the whole eggshell, because of the way that its kind of pointy at the ends then there's a gradual gradient outwards and back in, but if you crush it from the sides there's not enough gradient in the curve to distribute the force evenly throughout the shell. Hopefully that made sense.
Or, the ends act kind of like an archway but in 3d, very strong, the sides are curved too yes but its easy to imagine that an archway that is barely curved is going to be alot weaker than a proper archway
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When you're applying force to the ends, the force is distributed more evenly over the whole eggshell, because of the way that its kind of pointy at the ends then there's a gradual gradient outwards and back in, but if you crush it from the sides there's not enough gradient in the curve to distribute the force evenly throughout the shell. Hopefully that made sense.
Umm... it kind of made sense
Or, the ends act kind of like an archway but in 3d, very strong, the sides are curved too yes but its easy to imagine that an archway that is barely curved is going to be alot weaker than a proper archway
This made sense! Okay, thanks!
Does that mean that bridges with wider arches are weaker than those with narrower arches.
Say one bridge was modelled by y=-x2 and the other y=-0.5x2 would the first one be stronger than the second, assuming that they are made of the same marterials etc...?
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Yep
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There is also the issue of symmetry.
The curvature in two planes is not the same when squashing an egg on its side and the stresses are different. There is a very large curvature in the 'end to end' (North South) plane compared with smaller curvature in the 'Equatorial Plane' so the stress is not shared equally. On end, the arrangement is symmetrical and the stress is shared equally in all directions.
This more of a Physics / Technology question, really.
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There is also the issue of symmetry.
The curvature in two planes is not the same when squashing an egg on its side and the stresses are different. There is a very large curvature in the 'end to end' (North South) plane compared with smaller curvature in the 'Equatorial Plane' so the stress is not shared equally. On end, the arrangement is symmetrical and the stress is shared equally in all directions.
Uhm...hmm.... and what does that mean in English [:-\] [:I]
Is it similar to what Madidus_Scientia said?
This more of a Physics / Technology question, really.
Opps... [:I] [:I]
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What I'm saying is that the symmetry when you push against the end means that the forces are shared equally around the egg, making it stronger than then you push the side, when the stresses are concentrated into one part of the shell.
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Pressure= force/area right? [:-\] So say I pushed with a force of 10 N and the egg on its side had an area of 0.0002 m2 so the pressure = 10/0.0002 = 50000 Pa. And if I did the same with the egg on its tip, with an area of 0.0001 then wouldn't the pressure be 100000 Pa? Is that right? Or does the egg have a smaller surface area on its side than at the tips? [:-\]
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It's not just the 'pressure' that counts. The forces are there, all over the surface - transmitted almost sideways / parallel to the shell around the curves. There will always be a finite distortion as you push against anything - even a 'rigid' egg. The effect of this movement will be to change the forces acting around the surface and can produce high stress areas - particularly when they are not applied symmetrically.
Alternatively, think of a wide (nearly flat) arch and a narrow arch; which one would be stronger? The wide (large radius) arch would fail first. Pushing the side of the egg exposes the very widest arch to a force 'into it'. It will break first.
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Okay, thank you everybody!
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Does that mean that if the bottom of your foot is more arched, there will be more support/strength compared to if the sole of your foot was less archy?
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Yes - all things being equal. People with 'flat feet' get more tired when walking than people, like me, with an embarrassingly high arch.
embarrassing because it has repercussions on my toes. Can't win em all.
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Ah, well, that is interesting, thank you for clearing that one up sophiecentaur [:)]
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Oblate spheroid, that is the shape of an egg, in case you were wondering. What I'd really like to know is how a chicken knows what size your egg cup is?
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I thought it was prolate.
Isn't 'oblate' the word for the shape of the Earth?