2. 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

3. 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…

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

5. 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

6. 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

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

8. Advantages 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  SUV  Farmer’s tractors  Much more control in all vehicles w/ low COG

9. Animals  Low COG High COG

10. 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

11. Robots – Where is the COG? Where is this robot’s Gravity “Average Mass” Centered? A B C

12. Robots – Center of Gravity Is this robot’s gravity more centered at it’s starting point “A,” or in it’s current position, “B?” How do you know? A B

13. Robots – Center of Gravity How has the builder of this robot considered centering the gravity for the task that it has to accomplish?