Q. A boy ties a stone of mass $100\, g$ to the end of a $2\, m$ long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of $80\, N$. If the maximum speed with which the stone can revolve is $\frac{ K }{\pi} rev . / \min$. The value of $K$ is : (Assume the string is massless and unstretchable)
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