![A hollow circular shaft of inner radius 10 mm, outer radius 20 mm and length 1 m is to be used](https://www.gkseries.com/blog/wp-content/uploads/2023/10/A-hollow-circular-shaft-of-inner-radius-10-mm-outer-radius-20-mm-and-length-1-m-is-to-be-used.jpg)
Q. A hollow circular shaft of inner radius 10 mm, outer radius 20 mm and length 1 m is to be used as a torsional spring. If the shear modulus of the material of the shaft is 150 GPa, the torsional stiffness of the shaft (in kN-m/rad) is____________(correct to two decimal places).
Ans: 35.343
Sol:
![](https://www.gkseries.com/blog/wp-content/uploads/2023/10/Screenshot-1053.png)