CENTER OF

GRAVITY

By: Jordan Young, HannaH Simmons, Nik Schmidt, Renè Chatneuf, Katrina Schmidt, MaryAnne Cavasos

Center of Gravity

An object’s center of gravity is the point at the center of the object’s weight distribution.

For a symmetrical object the center of gravity is at the geometrical center.

For an irregularly shaped object the center of gravity is toward the heavier end.

If an object is moving with rotational motion then it is moving about it’s center of gravity.

Center of Mass The center of gravity is also called the center

of mass. This is the point of average mass distribution

for an object. An object in outer space where gravity force

is almost zero then the object has a center of mass but no center of gravity.

If you threw a lopsided object the center of gravity would follow a parabolic path but the object would wobble because of the distribution of mass.

Locating the Center of Gravity

The center of gravity for uniform object is at the midpoint. Supporting it at that point would support the whole object.

For a suspended object the center of gravity will hang directly below the point of suspension.

The center of gravity for a ring for example would exist where there is no actual material.

A plumb bob can be used to find the center of gravity for an irregularly shaped object.

Toppling

An object will topple when the center of gravity extends beyond it’s support base.

If the center of gravity is above the base the object will remain upright, such as the Leaning Tower of Pisa.

The support base of an object is not always solid, such as a chair.

Stability It is nearly impossible to balance a pen upright

because the base of the support is inadequate for the point but it is adequate for the flat end.

When an object is balanced and any displacement raises its center of gravity it is in a stable equilibrium.

When an object is on its side and its center of gravity is neither raised or lowered with displacement it has a neutral equilibrium.

Any object that hangs with its center of gravity below its point of support it is in stable equilibrium

Stability (cont.)

If a building’s center of gravity is below ground then it is impossible for it to fall over while it is intact.

If the object is heavier than an equal volume of water, it will be more dense than water and sink.

Center of Gravity of People

When you stand erect with your arms hanging at your sides your center of gravity is within your body.

The center of gravity is slightly lower in women than it is in men because women tend to be proportionally larger in the pelvis and smaller in the shoulders.

In children the center of gravity is approximately 5% higher because of their proportionally larger heads and shorter legs.

When you stand your center of gravity is somewhere above your support base which is in the area bound by your feet

Bibliography

Hewitt, Paul G. "Center of Gravity." Conceptual Physics: A High School Physics Program. Menlo Park, CA: Addison-Wesley, 1987. 119-30. Print.