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An object of mass 4 \mathrm{~kg} is moving along x-axis and its \mathrm{P E} as a function of \mathrm{x} varies as \mathrm{U(x)=4(1-\cos 2 x) J}, the time period of small oscillations is-
 

Option: 1

\pi\: \mathrm{sec}





 


Option: 2

2 \pi \: \mathrm{sec}


Option: 3

4 \pi\: \mathrm{sec}


Option: 4

2 \: \mathrm{sec}


Answers (1)

best_answer

\mathrm{F=-\frac{d U}{d x}=-\frac{d}{d x}[4(1-\cos 2 x)]}

\mathrm{ f=-8 \sin 2 x } ________(1)

For small \mathrm{ x }

\mathrm{ \sin 2 x=2 x }

\mathrm{ f=-8 \times 2 x }

\mathrm{ or \: \: a=\frac{f}{m}=-\frac{8 \times 2 x}{4}=-4 x }

on comparing with \mathrm{ a=-\omega^2 x }, we have

\mathrm{ \omega=\sqrt{4}\: \mathrm{rad} / \mathrm{s} \quad \& \quad T=\frac{2 \pi}{\omega} }

\mathrm{ \omega=2 \: \mathrm{rad} / \mathrm{s} \quad T=\frac{2 \pi}{2} }

                             \mathrm{ T=\pi\: \mathrm{sec} }

Hence option 1 is correct.




 

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