Answer:

Step-by-step explanation:
Given that
Diameter of shaft=3 in (1 in=0.0254 m)
Bending moment=3200 lb-ft (1 lb-ft=1.35 N-m)
We know that bending stress in circular shaft given as

Where M is the bending moment and d is the diameter of shaft.
Given that M=4338.61 N-m
d=0.0672 m
Now by putting the values

So
