Werid physics question

[Evan]

Frills, thanks for reminding me of that scene, jackass. I might go throw up now. [img]/images/graemlins/frown.gif[/img]

Evenkeal, Couldn't the same argument be made for jumping into water? Clearly at some density you're going to displace the straws and fall. I mean, if I threw a dumbell in there it would fall, right? Or like a block of lead. What makes water get out of the way that wouldn't apply for these straws?

bobman, what would stop you at the 5-10 ft mark? It seems like if you get your hole body under the straws you should just keep falling, doesn't it?

punk, I agree spreading out like you're corwad surfing would be the best strategy.

[Evan]

[ QUOTE ]
how was the pit filled? that's extremely important.

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You can answer for two scenarios:

1) all aligned parellel, as if the pit were a big box of them packed by the facotry
2) randomly, as if you just dumped a giant box of them into the pit

[TimM]

[ QUOTE ]
Evenkeal, Couldn't the same argument be made for jumping into water? Clearly at some density you're going to displace the straws and fall. I mean, if I threw a dumbell in there it would fall, right? Or like a block of lead. What makes water get out of the way that wouldn't apply for these straws?

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Water is a fluid. At some depth, the pressure on the straws will be so high, and they will be packed so tightly that your weight is not enough to overcome the friction between them.

[Borodog]

Clearly this needs to be investigated empirically. Post a trip report when you're done.

And mygut instinct as a physicist is that if the pit were filled rancomly, you'd be able to stand right on top of them and walk without any problem at all.

I have a friend who may be able to run a simulation for you. I'll get back to you on it.

[Evan]

[ QUOTE ]
Clearly this needs to be investigated empirically. Post a trip report when you're done.

And mygut instinct as a physicist is that if the pit were filled rancomly, you'd be able to stand right on top of them and walk without any problem at all.

I have a friend who may be able to run a simulation for you. I'll get back to you on it.





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Unfortunately I do not have access to a pit.

If your friend can actually answer this that would be awesome.

[Borodog]

He does particulate flow simulations. The question would be whether or not he can manage particles of the shape and physical characteristics of straws.

[Double_A]

I think it depends on the volume of space the straws occupy vs the volume of air. If the straws were densely packed, obviously you would just land on top of them and be safe. However, if they were just thrown in and filled up to 10 ft below the top of the pit, my guess is you would just kinda float/sink to the bottom of the pit.

[bobman0330]

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bobman, what would stop you at the 5-10 ft mark? It seems like if you get your hole body under the straws you should just keep falling, doesn't it?

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Not to me, but I see what you're saying. I'm thinking that the pit full of straws will be springy to some extent. So when you fall in, you compress the straws for a while, but eventually there's no more give in the column of straws and they begin to support your weight. If you can spread-eagle before you hit the straws, it will probably hurt like hell, but you'll have a much better chance of escaping.

[Hellrazor]

[ QUOTE ]
[ QUOTE ]
how was the pit filled? that's extremely important.

[/ QUOTE ]
You can answer for two scenarios:

1) all aligned parellel, as if the pit were a big box of them packed by the facotry
2) randomly, as if you just dumped a giant box of them into the pit

[/ QUOTE ]


1) Sink quickly, as you are far denser than the straws. Displacement of the straws are easier as they are all aligned not creating any artificial "structure" type arrangements that would add to their strength in supporting you. The rounded edges all aligned with each other would make the "rolling" of the straws out of the way very easy.

2) Sink somewhat less rapidly then 1 above, as the straws would find resistance in moving to accomodate your falling volume displacing them. But you'd still sink, because your density is greater than the straws and most likely still greater than the straws density + any tensile strength added by random artificial structures.

If you could square off the straws and arrange them its probably possible to create a planned structure of them that would support you enough to keep you afloat.

All guesses of course.

[TimM]

[ QUOTE ]
And mygut instinct as a physicist is that if the pit were filled rancomly, you'd be able to stand right on top of them and walk without any problem at all.

[/ QUOTE ]

Not sure, these things do flex a bit.

I was thinking of an inground pool filled with sand. You could walk right across it, but your feet will sink into the sand about an inch or two. Add the right amount of water and you get quicksand though.