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**Su165****Member**- Registered: 2005-03-07
- Posts: 1

Can anyone give me a hand with this, cause I'm stumped and can't remember exactly how to go about solving this.

here's the eqn

m[d^2x/dt^2 + wsubo^2 x] = F cos wt

I'm supposed to show that x(t) = xsubo cos wt

w is the incident freq

wsubo is the resonant freq

m is mass

I'm guessing it has to be shown by undetermined coefficients but I can't find the right path exactly.

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,619

A bit outside my area, but I found a website that has ALL sorts of stuff about harmonic motion which could help here

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

Um...what kind of algebra is that?

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,619

The difficult kind ! It has calculus in it.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

How old are you expected to be to be at that standard?

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,619

Depends on where you live. Some countries start Calculus in the final year of high school.

But usually Universities teach it in the first year.

I was thinking of putting a small introduction to it on this website.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

I'm only thirteen!

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,619

You're doing well!

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

Thank you.....but how do you know....?

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,619

You noticed, and were curious about, the algebra. You write well, too.

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**Roraborealis****Member**- Registered: 2005-03-17
- Posts: 1,594

You're such a nice person!

School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?

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