A woman is holding a 3.5-kg sphere in her hand with the entire arm held horizontally as shown in the figure. A tensile force in the deltoid muscle prevents the arm from rotating about the shoulder joint O; this force acts at the 23° angle shown. Determine the force FD exerted by the deltoid muscle on the upper arm at A and the x- and y-components of the force reaction at the shoulder joint O (positive to the right and up). The mass of the upper arm is my= 2.0 kg, the mass of the lower arm is m₁ = 1.2 kg, and the mass of the hand is mч= 0.4 kg; all the corresponding weights act at the locations shown in the figure. Deltoid muscle x Answers: FD 3.5(9.81) N 23° WU VWL WH 122 mm 129 mm 414 mm 632 mm- FD= i Ox Oy= = i י N N N Z Z Z

Problem 3: Locate the centroid x of the area. y = -b-

Locate the centroid of the area shown below. 12" Y-axis 4" x = 1.94; y = 4.66 O x =4.66;y=1.94 x =0.00;y = 4.66 O x = 4.66;y=0.00 6" 9" 2" -X-axis

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