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/sci/ - Science & Math

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9457743 No.9457743 [Reply] [Original]

How would one model the dynamics of this string shooter?
https://www.youtube.com/watch?v=rffAjZPmkuU

In particular how the hell does one model the dynamics of rigid string? What I'm wondering is if one could modify the design to make a string shooter capable of supporting stuff sort of like a launch loop.

>> No.9458140

Bump

>> No.9458160

>>9457743

Lagrangian for a continuous system.

You essentially have infinite degrees of freedom since you can treat each little section of the string as a mass coupled to each section next to it, but if there would be infinite of them.

The real question then becomes "how does the potential energy change as I pull on this string?"

If it's truly rigid then the potential energy would just be a unit step function multiplied by infinity, with a defined "natural length" for any given section such that if you pull it farther than that you'd have infinite energy.

If might be easier (and closer to reality) to simulate though if you just make a step function with a REALLY steep slope, such that the potential varies linearly (or maybe quadratically ) with any given arc-length.

I actually ran some simulations using those, though not all of them look that accurate. Partly might be due to shitty coding.

>> No.9458180

bump

pls
knowing this would be very very useful and interesting pls pls pls pls

>> No.9458253

Man I love Bruce Yeany, I'd die to have him as my dad.

>> No.9458270

>>9457743

You'll need to know string theory

>> No.9458452
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9458452

>>9458270

>> No.9458454

>>9457743
Where do you get continuous string?

>> No.9458458

>>9457743
differential equations

>> No.9458795

>>9458458
Of course, but which ones?

>> No.9458875

>>9457743

Chain physics
Neal Stephenson talks about it in Seveneve. the String gun would be a forced example of the chain fountain
https://www.wired.com/2013/07/the-physics-of-that-gravity-defying-chain-of-metal-beads/

as for the math of the propagation of the wave of perturbation, I dunno!

>> No.9458903
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9458903

>>9457743
Is this string theory?

>> No.9458912

>>9458875
Very cool.

>> No.9459176

bump

>> No.9459209

>>9457743
>write PDE describing conservation of momentum in string
>discretize and solve
>????
>profit

also rigid bodies aren't real

>> No.9459700

>>9459209
How? I also need to take into account friction and contact

>> No.9461033

Bump

>> No.9462547

Bamp

>> No.9462704

>>9458454
nylon melts under the flame of a candle. join two ends while hot

>> No.9465087

Bump