Two solid metal shafts, are connected by the gears shown. Given:

$a=40mm$

$b=160mm$

$c=30mm$

$d_1=50mm$

$d_2=120mm$

$G=170$GPa

Answer the following:

a$)$ If the applied tourque on shaft AB$,$ T $=210$ N$.$m$,$ then the tourque generated in shaft $EF=$ N$.$m $[$Absolute value$]$

b$)$ Discard your answer in Part $($a$)$ and considering $T_{EF}=550$ N$.$m and diameter ${?}_{EF}=50mm,$ then the maximum shear stress in shaft EF $=$

MPa $[$Absolute value$]$

c$)$ If the angle of twist of shaft $AB$ is not to be greater than $2,$ and considering the applied torque on shaft $AB=210$ N$.$m$,$ then the minimum required shaft $AB$ diameter $=$

mm