Question

4. A person's in the figure arm is illustrated al find the center of mass (CM) of this arm given the following in formation: The upper arm has a mass of 2.5kg and the CM is 0.18m above the elbow; the lower arm has a mass of 1.6 Kg and ja CN located at 0.12 m to. the right of the elbow; The hand has a mass of 1.64 kg and it's CM is 0.4om to the right of the elbow (b) A o.14kg ball is placed in. the palm of the hand. If the

Answer 1

a)

let m1 = 2.5 kg
x1 = 0, y1 = 0.18 m

m2 = 1.6 kg
x2 = 0.12 m, y2 = 0

m3 = 0.64 kg
x3 = 0.4 m, y3 = 0

coardinates of center of mass,

Xcm = (m1*x1 + m2*x2 + m3*x3)/(m1 + m2 + m3)

= (1.6*0 + 1.6*0.12 + 0.64*0.4)/(2.5 + 1.6 + 0.64)

= 0.0945 m

Ycm = (m1*y1 + m2*y2 + m3*y3)/(m1 + m2 + m3)

= (1.6*0.18 + 1.6*0 + 0.64*0)/(2.5 + 1.6 + 0.64)

= 0.0607 m

b) m4 = 0.14 kg
x4 = 0.4 m, y4 = 0.037 m

coardinates of center of mass,

Xcm = (m1*x1 + m2*x2 + m3*x3 + m4*x4)/(m1 + m2 + m3 + m4)

= (1.6*0 + 1.6*0.12 + 0.64*0.4 + 0.14*0.4)/(2.5 + 1.6 + 0.64 + 0.14)

= 0.103 m

Ycm = (m1*y1 + m2*y2 + m3*y3 + m4*y4)/(m1 + m2 + m3)

= (1.6*0.18 + 1.6*0 + 0.64*0 + 0.14*0.037)/(2.5 + 1.6 + 0.64 + 0.14)

= 0.0601 m