The internal torque over the 0.5-m-radius solid cross-section has been determined to be ( 100π N ⋅ m ) in the counterclockwise direction. What is the magnitude of the shear stress at point P due to the torque?
a) ( 200π/π N/m² )
b) ( 100 N/m² )
c) ( 200 N/m² )
d) ( 50 N/m² )