Extracted text: A hollow aluminum driveshaft has the dimensions shown and is subjected to the torques shown. If the failure shear strength of the aluminum is 25 ksi, what is the factor of safety for the driveshaft? Give a number with three significant figures for your answer. 326 ft-lb outside dia = 2 in inside dia = 1.5 in 326 ft-lb outside dia = 2 in inside dia = 1.5 in %3D cross-section 6.5 ft