If the object has an irregular shape or its composition varies, the center of gravity is at the point where the object balances without rotating in any direction. If you try to balance an object at any point other than its center of gravity, it will rotate because the center of gravity is not supported. Imagine trying to balance an egg beater or a lamp on the tip of your finger. It isn’t easy to decide where you put your finger to balance it, is it? You would have to hold it and try balancing it at several points before you found the center of gravity.
How do you find an object’s center of gravity? The center of gravity is the point at which the object balances. Think of a gymnast on the rings. He is keenly aware of his center of gravity. He will stay balanced and not rotate only if he balances his mass about his center of gravity.
Try these fun exercises to play with center of gravity.
- Sit straight in a chair, with your back against the back of the chair. Fold your arms in front of you. Now try to stand up without leaning forward. Can you do it? Can you explain where your center of gravity is when you are sitting? Where does it need to go when you want to stand up? What is the only way to accomplish this?
- Stand against a wall, with your back to the wall. Place an object in front of you and try to pick it up without moving your feet. Can you manage it? Explain.
