A $75$ mm diameter solid shaft is supported on end bearing $4$ m apart. It carries a pulley weighing. $1\mathrm{.}75$ KN at its centre. It is$/$subjected to a torque of $1\mathrm{.}5$ kNm $.$ Ignoring the weight of the weight of the shaft, determine

i$)$ Equivalent torque to produce the same$-$maximum shear stress.

ii$)$ The maximum shear stress and

iii$)$ The principal stresses.