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A person bends over, and lifts an object of mass m = 28.5 kg while keeping the back parallel with the floor. The muscle that attaches 2/3 of the way up the spine maintains the position of the back. This muscle is called the back muscle or latissimus dorsi muscle. The angle between the spine and the force
in this muscle is è = 10°. Use the balance of torques and forces in the simplified graph shown in part (b) of the attached figure and take the mass of the upper body as M = 42 kg.
Find the x-component of the compressive force
in the spine. Hint: In the figure, W1 is the weight of the object being lifted and W2 is the weight of the upper body.