Question

biceps 2) Suppose that the dumbbell has a mass of 10.0 kg (so its weight equals 98.0 N) and the arm that holds it has a mass of 2.2 kg (with a weight of 21.6 N). The weight acts 3.0 cm from the elbow joint and we can think of all of the mass of the arm as at a distance of 14.0 cm from the elbow. Find the force in the biceps muscle if it attaches 3.1 cm from the elbow and makes and angle of 85" from the forearm. The angle from the horizontal equals 35" Mg mg a) Where's a wise place to locate the reference point (the Blue Ball of Death)? b) What angle will you use in the torque equation for the weight of the arm (mg) and the weight of the dumbbell (Mg)? c) Calculate the force in the biceps muscle needed to hold the arm and weights in this position. d) Why should you expect a large answer for the force in the biceps?

Answer 1

0 - 35° mg = 98.00 mg mg 2.2x9.8 N a is reference point should be located at elbow point. because we know all distance with respect to that point. torque e=řxř = rf. sina between angle force & position vector. that 90-35 = 55° both. same angle will be used for taking moment about elbow point. Fx 3.1xsing = mg x 14 sina + mag x 32xsina here angle is a= 90-0= © fx3 4x sings = 22x9-8x14x sin55+ 98x32xxin55 @ moment asm E because [f= 9119 N] get larger biceps force is smallest. f