When we hold a weight at arm’s length at the height of our shoulder, the deltoid muscle is largely responsible for keeping our arm and the object at their fixed height. to estimate the tension in the deltoid, we model the arm as in the drawing below, with all forces acting on the arm at the indicated distances from the origin (o). the arm’s mass is 10 kg and its weight �⃗ ( acts on the center of gravity (cg), while the small object’s mass is 6 kg, and it exerts a force �⃗*→, all the way at the end of the arm. � = 15°