Center of Gravity

We have been…

Can we…?

What path did they follow?

Both follow a parabolic path But bat wobbles around a certain point

Center of Gravity This point follows a parabolic path The rest does not

Center of Gravity is at the center of weight distribution

Symmetrical geometrical center

Not Symmetrical toward heavier end

Wobbling Toys Dense Bottom

Wobble Toys

Center of Gravity Sometimes called Center of Mass

Point of average mass distribution For objects near – interchangeable In space, center of mass (NOT gravity)

Center of Gravity of Moon Closer to Earth than the center of mass Nearer parts pulled more by Gravity

But for everyday objects - same

Center of Gravity

Center of Gravity of Meter Stick Point where balance Entire weight behaves as if concentrated at one

point

Finding Center of Gravity Suspend an object and mark with a vertical line

Change point of suspension and mark 2nd line

Point of intersection is the Center of Gravity

Center of Gravity

Center of Gravity may be where no material is…

Lean Back?

Toppling – Why? “Weeble Wobble

Theorem” An object whose center of

gravity is above its base of support will not topple

If center of gravity outside area of support topple

Designs

Low Center of Gravity and Wide Base

Balancing Toys

Weighted so Center of Gravity vertically under support point with the remainder above

Center of Gravity and People

When you stand straight up, center of gravity in the body is 2-3 cm below belly button and centered between the front and back

Center of gravity lower in women

Center of Gravity and People

Touch Toes – Where is the Center of Gravity?

Center of Gravity and People

When Standing Center of gravity above support base (area

bounded by feet) Baby

Trouble coordinating center of gravity above feet when walking

Center of Gravity

Stand on Toes Smaller Base

Pregnant Woman Lean backwards so center of gravity is above the

base Pigeon

Jerks head so center of gravity is above supporting base

More Examples