Define angle of twist and angle of shear?

T is the applied torque or moment of torsion in Nm. ... ℓ is the length of the object the torque is being applied to or over. φ is the angle of twist in radians. G is the shear modulus, also called the modulus of rigidity, and is usually given in gigapascals (GPa), lbf/in2 (psi), or lbf/ft2.