Torque Static Equilibrium dditional Problem 1. In a physical therapy exercise, a

Question

Torque Static Equilibrium dditional Problem 1. In a physical therapy exercise, a woman holds a ball in her hand. This places the deltoid muscle in tension with a magnitude of F 675 N and directed 21 above the horizontal. See below. The weights of the humerus bone, wH, and hand, wa are given. The humerus bone connects to the scapula at point O, which can be treated as a hinge. There is a downward vertical hinge force of Hy163 N at this joint. Find the 1) horizontal hinge force, H, 2) the weight of the forearm bones, w, and 3) the weight of the ball, all. Assume the weight of the ball acts at the same point as the hand weight 1 m-1,000 mm] Woall- Deltoid muscle 21 125 mm 0N 130 mm 412 mm 635 mm

Explanation / Answer

a) Hx = 675 cos 21 degree

             = 630.2 N

b) balancing torque about hinge,

0= 675 sin 21 degree *125 - 30*130 - Wf*412 -635*6.5 - Wball*635

   22210 = Wf*412 + Wball*635

Also Wball +6.5+30 + Wf +163 = 675 sin 21 degree = 241.9

   Wball + Wf = 42.4 N

b, c) Wball =21.27 N, Wf = 21.13

Wf = 485 Wball

solving two variables,

   Wf = 108218/223 = 485.2 N

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.