You already know about your own center of gravity. You learned about it when you learned to walk, ride a bike, or move your body in almost anyway.
If you have ridden a bicycle, skated on roller skates or roller blades, or used a skateboard, you are familiar with trying to balance your body. You adjusted your center of gravity by leaning one direction or another without realizing it. When you are balanced, all of the forces acting on your body are balanced. You are successful at riding your bike. When you are unbalanced you fall to one side or the other of your bike.
Normally, when you are standing, your center of gravity is somewhere in the middle of your body, around your belly button. What happens if you put a heavy pack on your back? You might find that you have to lean forward a little bit to keep from falling backwards. This is because the pack shifts your center of gravity, and you are constantly working to keep it over your feet. Backpackers are careful to load their packs with the mass even and low, in order to keep their center of gravity closer to where they are familiar with it, and where it is more stable.
Sometimes the center of gravity is outside the body of the object. This may seem strange, but for an oddly shaped object, such as a gymnast, the force vectors might add up such that the center of gravity is somewhere in the air over the supporting point.
Center of Gravity
Where would you expect to find the center of gravity on your dinner plate?
