CENTER OF GRAVITY Center of Gravity COG DefinitionThe

CENTER OF GRAVITY

Center of Gravity (COG) Definition--The Point located at an object’s average position of the weight In other words…. The center of an object’s weight Symmetrical object’s, like a baseball the C of G would be in the exact center of object However other oddly shaped objects will find COG in any number of positions, depending on weight distribution COG

C. O. G. When objects rotate freely they must rotate about an axis through the COG Basically treat the object as if all its weight is concentrated at that one pt. In class demos…

C. O. G. --Balancing For an object to balance, and not topple… support must be directly below C. O. G.

Where C. O. G. is located Generally found in the middle of all the weight… Does not even have to be within, the object itself Ex. boomerang Will be located toward one side of an object where most of its mass is focused… Ex. Weebles COG gravity

Weebles Wobble, but they don’t fall down? ? ? Weebles have very low COG Whenever rolling it will roll to a stop when its COG is as low as possible This occurs when it is standing upright Also occurs for inflatable toy clowns Objects with a low COG are less likely to topple because of this principle Higher COG is, the easier to topple

Balancing Stuff Again, all that has to happen to balance, is for a support to be directly beneath COG

Advantage of low COG Athletic advantages wrestling—harder to takedown Football – “ “ “ �Both easier to drive power through their legs SUV’s …. Tip over all the time b/c COG is too high ESUVEE Farmer’s tractors Much more control in all vehicles w/ low COG

Deadliest Catch Pots on deck and freezing ice make boat top heavy… more likely to roll and sink Ballast tanks at bottom help lower boat’s COG

Animals Low COG High COG

T. Rex & Tails

Humans - Where is our COG? Just below our belly button Notice, support always below COG Bipedalism? ? Only mammals w/ this ability to walk on 2 legs Because of Evolution and how our legs changed to balance between steps is why we are only mammals to walk

Because our legs/hips evolved so that our support base (feet) were close together allows us to be Hip protruding from joint…. bipedal Apes and our early ancestors hips were constructed differently with a wide set base. Impossible to walk bipedal Creates inward angled femurs… Which makes feet close together…. Providing a stable/efficient base for walking upright

How to find COG….

Picking up Chair Demo Boys vs. Girls Why girls can do this but boys can’t? ? Different weight distribution of body types