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Differential Equation banter

You have the differential equation below. Prove the thing next to that. I can't do it so don't ask me for help, have fun xx

Edit: I now know how to do it. Alas, I still will not help to be evil
(edited 8 years ago)
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:colondollar:
*Quietly returns to basic C4*
Original post by Gome44
You have the differential equation below. Prove the thing next to that. I can't do it so don't ask me for help, have fun xx

Edit: I now know how to do it. Alas, I still will not help to be evil


Spoiler

This reminds me of the pendulum equation maybe??
Original post by Serine Soul
*Quietly returns to basic C4*


Random... But Audrey is a goddess

Spoiler

Original post by Student403
Random... But Audrey is a goddess

Spoiler


PRSOM

She's my WCW everyday :love:

I genuinely aspire to be like her :colondollar:
Original post by Serine Soul
PRSOM

She's my WCW everyday :love:

I genuinely aspire to be like her :colondollar:

That's awesome :awesome:
Reply 8
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Original post by Louisb19
This reminds me of the pendulum equation maybe??


Its a quadratically damped pendulum
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Original post by atsruser

Spoiler



Not the way I've been told to do it, but it looks like that would work :smile:
Original post by Gome44
You have the differential equation below. Prove the thing next to that. I can't do it so don't ask me for help, have fun xx

Edit: I now know how to do it. Alas, I still will not help to be evil


Surely just solve it in the usual way: form the characteristic equation, guess a particular integral, etc.
ayy lmao
is this FP2? two dots above the theta means second-order differential of theta right?
I think for OCR MEI it would be in the DE module, and other boards (aka boring ones) it would be in FP3.
And yes, two dots means second derivative. It's a notation invented by Newton that's used mainly in mechanics.
Original post by ConstatSententia
I think for OCR MEI it would be in the DE module, and other boards (aka boring ones) it would be in FP3.
And yes, two dots means second derivative. It's a notation invented by Newton that's used mainly in mechanics.


Nope, sadly despite the name OCR MEI's DE module is surprisingly bare. Only very basic things and it's obsessed with modelling rather than solving harder DEs.
(edited 8 years ago)
Original post by ConstatSententia
Surely just solve it in the usual way: form the characteristic equation, guess a particular integral, etc.


Nope, be carful you have sin⁡θ \sin{\theta} .

It's only solvable in terms of elliptic integrals I think (this is not what Gnome is asking for however).
(edited 8 years ago)
Original post by ConstatSententia
I think for OCR MEI it would be in the DE module, and other boards (aka boring ones) it would be in FP3.
And yes, two dots means second derivative. It's a notation invented by Newton that's used mainly in mechanics.


2nd order ODEs are covered in FP2 for Edexcel. You can't solve this with the methods that you learn at A-Level anyway.
Original post by Louisb19
Nope, be carful you have sin⁡θ \sin{\theta} .

It's only solvable in terms of elliptic integrals I think (this is not what Gnome is asking for however).




Original post by Louisb19
2nd order ODEs are covered in FP2 for Edexcel. You can't solve this with the methods that you learn at A-Level anyway.



Mathematica says it's unsolvable.
Original post by ConstatSententia
Mathematica says it's unsolvable.


It is but only in terms of elliptic integrals.

http://math.ucr.edu/home/baez/classical/pendulum.pdf
http://mathworld.wolfram.com/EllipticIntegraloftheFirstKind.html

The question he is asking is not about solving it though so it doesn't matter :smile:.

By the way the revolution is dead mate.
(edited 8 years ago)
Original post by Louisb19


nunc exibo quia mathematica pervecta nescio.
Reply 19
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Original post by Louisb19
It is but only in terms of elliptic integrals.

http://math.ucr.edu/home/baez/classical/pendulum.pdf
http://mathworld.wolfram.com/EllipticIntegraloftheFirstKind.html

The question he is asking is not about solving it though so it doesn't matter :smile:.

By the way the revolution is dead mate.


While the normal pendulum equation is solvable with elliptic integrals, the quadratically damped pendulum is not unfortunately.

Only numerical methods can be used to evaluate t at certain theta (incidentally I took this from one of my Matlab projects)

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