The angle of twist for a shaft subjected to twisting torque can be expressed by the following equation: where TL JG = the angle of twist in radians T = applied torque (N-m) L = length of the shaft in meter (m) J = shaft's polar moment of inertia (measure of resistance to twisting) G = shear modulus of the material (N/m) What is the appropriate unit for J, if the preceding equation is to be homogeneous in units?