Problem 7.60 A l TABLE 7-1 Center of Mass of Parts of Typical Human Body, given
ID: 2304368 • Letter: P
Question
Problem 7.60 A l TABLE 7-1 Center of Mass of Parts of Typical Human Body, given as % (full height and mass = 100 units) Distance of Hinge Hin Points () Points from Floor ( %) Center of Mass () 1% Height Above Floor) Percent Mass oints) 69% 91.2% 81.2% Head Trunk and neck 93.5% 71.1% Base of skull on spine Shoulder joint Hip joint Knee joint Ankle joint 46.1% 4.2% 1.7% 21.5% dbow 62.2%" Upper arms Lower arms Hands 7 1.7% wrist 46.2% 52.1% 43.1% Upper legs (thighs) 42.5% 28.5% 18.2% 9.67% Lower legs Feet Body CM 58.0% 1 100.0% : For arm hanging vertically Suppose that the jumper was initilly in a position such that his arms and lower legs were hanging verticll, an & neck head, arms, and hands are tited down by 15, thighs are horizontal and lower legs are hanging verticaly The angle bExplanation / Answer
let the total height of the person be h
then from the definition of center of mass
distance of center of mass is from the foot is x
x = sum of( mi*xi)/sum of(mi)
here mi is mass of individual body part
and
xi is the location of the center of mass of that body part form the feet
hence
from the given data
x = h(1.8*3.4 + 18.2*9.6 + 42.5*21.5 + 43.1*1.7 + 55.3*4.2 + 71.7*6.6 + 71.1*46.1 + 93.5*6.9)/(3.4 + 9.6 + 21.5 + 1.7 + 4.2 + 6.6 + 46.1 + 6.9)
x = 5796.2*h/100 = 57.962h
hence com of a person is 57.962% of the height of the person from the feet
hence form the median line of the thighs it is 57.962 - 42.5 = 15.462% hogher
positive direection of y is downwards
hence
y = -15.462% of total heigth from the median line of the thigh