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Movimiento oscilatorios: libre, amortiguado, forzado.

Movimiento oscilatorios: libre, amortiguado, forzado.

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Oscilador armónico <strong>forzado</strong><br />

Segunda ley de Newton:<br />

F(t) = Fext cos(ωt)<br />

m x¨ = −kx − b x˙ + Fext cos (ωt), x¨ + b<br />

m x˙ + ω 0 2 x =<br />

Fext<br />

m cos(ωt)<br />

Solución particular de la ecuación anterior:<br />

y¨+ b<br />

m y˙ + ω 0 2 y = Fext<br />

m eiωt<br />

x = Ae iωt<br />

<br />

A −ω2 + b<br />

m iω + ω0 2<br />

<br />

eiωt = Fext<br />

m eiωt<br />

A =<br />

−ω2 + b<br />

<br />

Fext/m<br />

−ω 2 + b<br />

m iω + ω 0 2<br />

m iω + ω 0 2 = Re iφ<br />

R = (ω 0 2 − ω 2 ) 2 +<br />

A = Fext<br />

mR eiφ<br />

tan φ =<br />

bω<br />

m<br />

2<br />

bω<br />

m<br />

ω 0 2 − ω 2<br />

x(t)=Re(y(t))= Fext<br />

cos(ωt + φ)<br />

mR<br />

14

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