Question

A stone is whirled in a vertical circle at the end of a string. When the stone is at the highest position, the tension in the string is
a. Minimum
b. Maximum c.
Greater than the weight of the stone
d. Equal to the weight of the stone​

Answer 1

Tension is minimum (Option a)

Let's assume that stone of mass m is moved in a vertical circle of radius r such that the tension at the highest point is T.

• Let the velocity at highest point be v.

Now, from FREE BODY DIAGRAM, we know that:

$T + mg = \dfrac{m {v}^{2} }{r}$

$\implies T= \dfrac{m {v}^{2} }{r} - mg$

Now, at highest point, the centrifugal force and the weight of the particle is in opposite directions. Hence the net tension is least.

$\star$ Hope It Helps

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