Subject:
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Re: Physics/Materials geek question
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Newsgroups:
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lugnet.off-topic.geek
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Date:
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Sat, 5 Jan 2002 20:07:32 GMT
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Viewed:
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123 times
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In lugnet.off-topic.geek, David Goeb writes:
OK, thanks, I will think about keeping slack in the tent when I start
throwing rocks, that is easier to put in than tin plate.
I'm sorry, I put a rubber eraser "rock" on a postal scale, rounded up the
metric conversion in my sleepy head and underestimated the volume. The
"rock" was more like 8 cubic cm and 50g.
So, pick a pebble from 1 to 10g instead.
Now that I have got a book out, lead is 11.34 g/cm3. Calcium carbonate
ought to be around 1 g/cm3.
The tent needs to be portable to screen a field operator with his LCD
computer display from flying rocks. I guess I can require 10 cm of headroom,
too!
I'm thinking of how to set up experiments. What is a good way to build a
rock thrower you can calibrate? Maybe a catapult powered by a dropped weight....
New idea: since the operator is carrying eye protection anyway, get a giant
goggle for the LCD screen and forget the tent...
> Oh and more to the point What are those rocks made of to get that mass?
> Lead works out as less than 20/cm3...
>
> Actually the distance between tie points and overall stress that the
> tent wall is at will make the most difference. Take for example a
> worst case of honeycomb of 2cm cells allowing no slacking to take up
> the force(MOI) and light-Tin plate would be minimum. Or we could
> have more slack and distance to absorb impact say 4mm rubbercloth
> at 1m (hexes again if you like or sq cells) and make sure you avoid
> the 10cm nearest the wall.<grin>
>
> But just a early morning had'only'single'cup'o'joe'so'far answer.
>
> Best
> DaveG
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Message has 1 Reply:
 | | Re: Physics/Materials geek question
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| (...) Concrete 2.4-ish and so are most non-ore rocks sandstone etc (Gieck 7th ed) (...) That was an offhand worst deformation with minimum attachments guess. You may need only 5 as 80% of the V will be lost by then anyway. (...) You got it, that (...) (23 years ago, 5-Jan-02, to lugnet.off-topic.geek)
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Message is in Reply To:
| | Re: Physics/Materials geek question
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| (...) Did you want full FEA on that or will rough back of the hand range do? Oh and more to the point What are those rocks made of to get that mass? Lead works out as less than 20/cm3... Actually the distance between tie points and overall stress (...) (23 years ago, 5-Jan-02, to lugnet.off-topic.geek)
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