The maximum and minimum shear stresses in a hollow circular

The maximum and minimum shear stresses in a hollow circular shaft of outer diameter 20 mm and thickness 2 mm, subjected to a torque of 92.7 Nm will be

1. 59 MPa and 47.2 MPa
2. 100 MPa and 80 MPa
3. 118 MPa and 160 MPa
4. 200 MPa and 160 MPa

	τ	=	T
	r		J

τ_max =	T.r_max
	J

=	92.7 × 10 × 1000
	(π/32) × (20⁴ - 10⁴)

≈ 100 N/mm²
τ_max is at r = 16/2 = 8 mm
τ_max = (100/10) × r_min = 80 N/mm² = 80 mPa