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22
awarded  Nice Question
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Apr
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comment How far does a trampoline vertically deform based on the mass of the object?
I don't think a small angle approximation is valid for a trampoline. E.g. a typical circular garden trampoline has height ~R; so a heavy bounce would dip at least R/2 -> 30 degrees.
Apr
18
comment Basic explosion physics - determining force
Just a quick note re angles - there's nothing wrong with the angle being negative. sin & cos are defined for any angle from $-\inf$ to $+\inf$, with a period of 360 degrees (or 2pi radians).
Mar
31
comment Calculate stainless steel pole necking limit
... [cont]: If you're interested in this kind of thing, there's plenty more to read on the internet. E.g. the Singapore tunnel collapse from a few years ago was caused in part because a certain detail was changed by the contractor without properly considering stability (buckling), and this subsequently failed. scribd.com/doc/6231559/DESIGN-AND-FAILURE-OF-SINGAPORE-TUNNEL
Mar
31
comment Calculate stainless steel pole necking limit
@Anna: Sorry for the late reply. The Wikipedia page on buckling is a reasonable introduction. Or a degree in structural engineering ;-). The main point I meant to get at is that for a complex setup like this, it's important to consider every failure mode. It's rare to find a real-world scenario that requires a simple stress calculation. Sadly also most buckling calculations are very complex (except for very simple structures) so it's not normally possible to calculate for them directly in a situation such as this. ...
Mar
10
revised Calculate stainless steel pole necking limit
Update: bracket is a weak point too.
Mar
10
comment Calculate stainless steel pole necking limit
@ Dave: (without knowing the full details of the joint) - I think the weakest point in the system won't be the joint between the arm and bracket, but between the bracket and pole. Clearly the arm is designed to be bolted to the wall, so whatever bolts would be used for that must be strong enough to make the equivalent join to the bracket. Assuming the holes in the bracket are same / similar distance apart as those in the bracket - if they're significantly closer together the forces will be larger.
Mar
9
comment Calculate stainless steel pole necking limit
Down-voting for the concerns Georg raises in comments to his answer. There's no explanation (or reason as far as I can see) to go from $strain = stress/Young modulus$ to $r = pressure rating / m.g$. The answer makes no mention of buckling and doesn't look at how the arm is attached to the pole.
Mar
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Mar
9
answered Calculate stainless steel pole necking limit
Jan
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answered “Magnetic mnemonics”
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answered Why does measured pressure change over time in closed hose with temperature gradient
Dec
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answered Simple three-body-problem?
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awarded  Quorum
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answered Why does the (relativistic) mass of an object increase when its speed approaches that of light?
Nov
25
answered Doppler's effect use