What is the tangential stress on the cross-section $PQRS$?

$A$ bob of mass $10\, kg$ is attached to a wire $0.3\, m$ long. Its breaking stress is $4.8 \times 10^7\, N/m^2$. The area of cross-section of the wire is $10^{-6}\, m^2$. The maximum angular velocity with which it can be rotated in a horizontal circle is ....... $rad/sec$.

The maximum possible height of a mountain on Earth is approximately (elastic limit of mountain rock $= 30 \times 10^7 \ N m^{-2}$,average density of mountain rock $= 3 \times 10^3 \ kg m^{-3}$,$g = 10 \ m s^{-2}$). (in $km$)

If the length of a wire is reduced to half,then it can hold the ......... load.

$A$ body of mass $10 \, kg$ is attached to the end of a wire of length $0.3 \, m$. If the breaking stress of the wire is $4.8 \times 10^7 \, N/m^2$ and its cross-sectional area is $10^{-6} \, m^2$,what is the maximum angular velocity in $rad/sec$ with which it can be rotated in a horizontal plane without breaking the wire?

Two blocks of masses $1 \,kg$ and $2 \,kg$ are connected by a metal wire going over a smooth pulley. The breaking stress of metal is $\frac{40}{3 \pi} \times 10^6 \,N m^{-2}$. What should be the minimum radius of the wire used if it should not break (in $mm$)? $(g = 10 \,m s^{-2})$