Dear student,

When a shaft is subjected to a twisting moment every cross section of the shaftwill beundera tensile stress .

Tensile stress - Tensile stress is defined as the force per unit area induced in the body by response to externally applied force, which tends to stretch the body. Eg - The cable of a crane.

And when the material is under tension ( by a rope or string or any external force ), then it's called tensile.