Question

The arm in the figure below weighs 36.0 N. The force of gravity acting on the arm acts through point A. Determine the magnitudes of the tension force F, in the deltoid muscle and the force F exerted by the shoulder on the humerus (upper-arm bone) to hold the arm in the position shown. (Enter your answers to at least the nearest newton.) x Your response is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in Enter a number. n. Carry out all intermediate results to at least four-digit accuracy to minimize roundoff error. N XN KO - - - - - - - A------------ o " 0.080 m -0.290 m -

Answer 1

here,

weight of arm , W = 36 N

taking moment of force about the point O

Ft * sin(12) * 0.08 - W * 0.290 = 0

Ft * sin(12)* 0.08 = 26 * 0.29

Ft = 453 N

the magnitude of tension force is 453 N

and

equating the forces horizontally

Ft * cos(12) = Fs * cos(theta)

453.3 * cos(12) = Fs * cos(theta) .....(1)

and

equating the forces vertically

Ft * sin(12) - W = Fs * sin(theta)

453.3 * sin(12) - 36 = Fs * sin(theta)

58.2 = Fs * sin(theta) ....(2)

from (1) and (2)

Fs = 447 N