Activity $4$ :

You have completed the tasks that your boss lefi you to do prior to his return, so you now have time to resume your normal activites in Automotive Design Suppori. The R&D department have requested some hand calculations to support their development work, in which they are experimenting with a range of drive shat materials

Task $4$:

a$)$ An internal combustion engine of $100$ horsepower $($hp$)$ transmits power to the car wheals of an automobile at $600$ revimin $($ rpm $)$ Neglecting any trarsmission iosses, desermine the minimum permissibie dameter of the solid corcular section steel shaf if the maximum shear stress in the shaft is limied to $75$ MPa $.$ What will be the resulting angle of twist of the shaft due to the applied torque, over a length of $1$ m $?$ Given that the rigidfy modulus. $G=50$GPa. $($Note that $1hp=745\mathrm{.}7W).$

b$)$ If the shath in $4$ a was replaced by a holow tube of the same external diameter, hut of wal thickness $0\mathrm{.}01$ m $,$ what would be the maxmum shear stress in the shaft due to the same appied torque, and the resuling twist of the shaft? The material properties of the shaft inay be assumed to be the same as that above.