Question

A stone of mass 2 kg is attached to a string can withstand maximum tension 200N.what is the maximum speed that stone can have during the whirling motion?

Answer 1

I assumed it is vertical circular motion.

At bottom point Tension is maximum

so
$Tmax = \frac{m {v}^{2} }{r} + mg \\ 200 = \frac{2 {v}^{2} }{r} + 20 \\ 180r = 2 {v}^{2} \\ {v}^{2} = 90r$
put value of length of string and get your answer!!