Solution to Problem 338 | Torsion of thin-walled tube

$T = 2At\tau$
 

Where:
$A = \pi ab = \pi(3)(1.5) = 4.5\pi \, \text{in}^2$
 

 

$T = 0.10 \, \text{in}$

$\tau = 8000 \, \text{psi}$
 

$T = 2(4.5Ï€)(0.10)(8000)$

$T = 22619.47 \, \text{lb}\cdot\text{in}$

$T = 22.62 \, \text{ kip}\cdot\text{in}$           answer