The function of time representing a simple

Question:

The function of time representing a simple

harmonic motion with a period of $\frac{\pi}{\omega}$ is :

  1. $\sin (\omega t)+\cos (\omega t)$

  2. $\cos (\omega t)+\cos (2 \omega t)+\cos (3 \omega t)$

  3. $\sin ^{2}(\omega t)$

  4. $3 \cos \left(\frac{\pi}{4}-2 \omega t\right)$


Correct Option: , 4

Solution:

Time period $\mathrm{T}=\frac{2 \pi}{\omega^{\prime}}$

$\frac{\pi}{\omega}=\frac{2 \pi}{\omega^{\prime}}$

$\omega^{\prime}=2 \omega \rightarrow$ Angular frequency of SHM

Option (3)

$\sin ^{2} \omega \mathrm{t}=\frac{1}{2}\left(2 \sin ^{2} \omega \mathrm{t}\right)=\frac{1}{2}(1-\cos 2 \omega \mathrm{t})$

Angular frequency of $\left(\frac{1}{2}-\frac{1}{2} \cos 2 \omega t\right)$ is $2 \omega$

Option (4)

Angular frequency of SHM

$3 \cos \left(\frac{\pi}{4}-2 \omega t\right)$ is $2 \omega$

So option (3) \& (4) both have angular frequency $2 \omega$ but option (4) is direct answer.

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