University:
Boston University
Course:
CAS PY 252 | Principles of Physics 2
Academic year:

2024
Views:

167

Pages:

10
Author:

Clint W.

11.6 Center of Gravity of People The center of gravity of a person is not located in a fixed place, but depends on body orientation. 11.6 Center of Gravity of People When you stand erect with your arms hanging at your sides, your CG is within your body, typically 2 to 3 cm below your navel, and midway between your front and back. Raise your arms vertically overhead. Your CG rises 5 to 8 cm. Bend your body into a U or C shape and your CG may be located outside your body altogether. 11.6 Center of Gravity of People A high jumper executes a “Fosbury flop” to clear the bar while his CG nearly passes beneath the bar. 11.6 Center of Gravity of People When you stand, your CG is somewhere above your support base, the area bounded by your feet. • In unstable situations, as in standing in the aisle of a bumpy-riding bus, you place your feet farther apart to increase this area. • Standing on one foot greatly decreases this area. • In learning to walk, a baby must learn to coordinate and position the CG above a supporting foot. 11.6 Center of Gravity of People When you stand, your CG is somewhere above the area bounded by your feet. 11.6 Center of Gravity of People You can probably bend over and touch your toes without bending your knees. In doing so, you unconsciously extend the lower part of your body so that your CG, which is now outside your body, is still above your supporting feet. Try it while standing with your heels to a wall. You are unable to adjust your body, and your CG protrudes beyond your feet. You are off balance and torque topples you over. 11.6 Center of Gravity of People You can lean over and touch your toes without toppling only if your CG is above the area bounded by your feet. 11.6 Center of Gravity of People think! When you carry a heavy load—such as a pail of water—with one arm, why do you tend to hold your free arm out horizontally? 11.6 Center of Gravity of People think! When you carry a heavy load—such as a pail of water—with one arm, why do you tend to hold your free arm out horizontally? Answer: You tend to hold your free arm outstretched to shift the CG of your body away from the load so your combined CG will more easily be above the base of support. To really help matters, divide the load in two if possible, and carry half in each hand. Or, carry the load on your head! 11.6 Center of Gravity of People On what does the location of a person’s center of gravity depend?