Part A Calculate the force, F M required of the \"deltoid\" muscle to hold up th

Question

Part A

Calculate the force, FM required of the "deltoid" muscle to hold up the outstretched arm shown in the figure(Figure 1) . The total mass of the arm is 3.3 kg

Part B

Calculate the magnitude of the force FJ exerted by the shoulder joint on the upper arm

Part A

Calculate the force, FM required of the "deltoid" muscle to hold up the outstretched arm shown in the figure(Figure 1) . The total mass of the arm is 3.3 kg

Part B

Calculate the magnitude of the force FJ exerted by the shoulder joint on the upper arm

Explanation / Answer

Sum the moments about the shoulder joint. Notice that the force Fj produces no torque there.
M = 0 = Fm * 12cm * sin15º - 3.3kg * 9.8m/s² * 24cm
Fm = 249.9 N

B) vertical: Fv = Fm*sin15º - mg = 249.9N*sin15º - 3.3kg*9.8m/s² = 32.3 N
horizontal: Fh = Fm*cos15º = 241.3 N
Fj = (Fh² + Fv²) = 243.4 N

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