Wave Mechanics Question 535

Question: A simple harmonic oscillator of angular frequency $ 2,rad,{{s}^{-1}} $ is acted upon by an external force F = sin t N. If the oscillator is at rest in its equilibrium position at t = 0, its position at later times is given by:

Options:

A) $ \sin ,t+\frac{1}{2}\cos ,2t $

B) $ \cos t-\frac{1}{2}\sin ,2t $

C) $ \sin t-\frac{1}{2}\sin ,2t $

D) $ \sin t+\frac{1}{2}\sin ,2t $

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Answer:

Correct Answer: C

Solution:

[c] As we know, $ F=ma\Rightarrow a\propto For,,a\propto \sin ,t $
$ \Rightarrow \frac{dv}{dt}\propto \sin t\Rightarrow \int\limits _{0}^{0}{dV\propto \int\limits _{0}^{t}{\sin t,dt}} $

$ V\propto -\cos ,t+1 $

$ \int\limits _{0}^{x}{dx}=\int\limits _{0}^{t}{(-\cos t+1)dt} $

$ x=\sin ,t-\frac{1}{2}\sin 2t $