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Circular Motion — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsCircular Motion5 Marks
Question
A table with smooth horizontal surface is fixed in a cabin that rotates with a uniform angular velocity $\omega$ in a circular path of radius R (In figure). A smooth groove AB of length L(<$\theta$ with the radius OA of the circle in which the cabin rotates. A small particle is kept at the point A in the groove and is released to move along AB. Find the time taken by the particle to reach the point B.
✓

Answer


The cabin rotates with angular velocity $\omega$ & radius R
$\therefore$ The particle experiences a force $\text{mR}\omega^2$
The component of $\text{mR}\omega^2$ along the groove provides the required force to the particle to move along AB.
$\therefore$ $\text{mR}\omega^2\cos\theta=\text{ma}$
$\Rightarrow\text{a}=\text{R}\omega^2\cos\theta$
length of groove = L
$\text{L}=\text{ut}+\frac{1}{2}\text{at}^2$
$\Rightarrow\text{L}=\frac{1}{2}\text{R}\omega^2\cos\theta\text{ t}^2$
$\Rightarrow\text{t}^2=\frac{2\text{L}}{\text{R}\omega^2\cos\theta}$
$\Rightarrow\text{t}=\sqrt{\frac{2\text{L}}{\text{R}\omega^2\cos\theta}}$

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