Question 176 of 183

A stone of mass $m$, tied to a string is being whirled in a vertical circle with a uniform speed. The tension in the string is

Athe same throughout the motion.Bminimum when the rope is in the horizontal position.Cminimum at the highest position of the circular path.Dminimum at the lowest position of the circular path.

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Answer: (C) minimum at the highest position of the circular path.

As the speed is constant, centripetal force required towards the centre of the circle will be same. At the top, direction of gravitational force and tension acting on the object will be same. Therefore, we can write,
$mg+T=\dfrac{m{v}^{2}}{r}\Rightarrow T=\dfrac{m{v}^{2}}{r}-mg$.
Clearly in this case, tension in the string will be minimum.

JEE Main Physics practice question on Work Energy Power (Circular motion), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.