A shank has a moment of inertia about the knee joint of 0.18 kg∙m^2. Assume that the quadriceps muscles (vasti and the rectus femoris) contract to extend the knee. If the vasti produce a torque of 0.4 Nm about the knee joint, what torque (in Nm) about the knee joint must the rectus femoris produce to cause a shank angular acceleration of 23.2 rad/s^2?