1. The problem statement, all variables and given/known data Rotator cuff strength test. Patient's elbow is flexed 90 deg. while the shoulder is abducted 90 deg. and externally rotated 90 deg. The therapist applies pressure to the dorsal surface of the hand/wrist. If this is the patient's dominant arm, and the length of her upper arm is 0.25 m and the distance from the elbow to the point the therapist applies the force is 0.20 m, answer the following: a) If the therapist is applying 40 N force, what is the internal moment this muscle group must generate to maintain a constant position / static equilibrium? b) If the muscle group can generate 14 Nm of torque when activated maximally, what is the greatest force the patient can resist before the arm starts to move? Assume z-axis runs through elbow / upper arm / shoulder. 2. Relevant equations Torque = F * r. 3. The attempt at a solution I have dealt with statics before usually in 2D. It seems more like a 3D problem and I'm a bit lost. The force is applied from the z-axis if we consider forearm be x-axis and lower arm be y-axis here. How do I project the forces and make the overall torque equal to 0 (since it's static equilibrium)?