#### What is center of gravity and why is it important? How can we find the location of the center of gravity of different objects?

## Center of Gravity

CENTER OF GRAVITY, the point at which the gravitational attraction of a body may be considered to be concentrated. Since gravitational attraction depends on mass, the mass of the body may also be considered to be concentrated at this point. For this reason, the center of gravity is also known as the center of mass.

The fact that alli the mass and weight of a body may be taken to be acting at a single point greatly simplifles many calculations. For example, the motion of a spinning baton thrown into the air appears to be rather complex. Actually, while the baton rotates about its center of gravity, the center of gravity itself moves through a simple arc.

The center of gravity of a body may or may not be a point on or within the body. For bodies of regular geometrical shape and uniform denSity, it is at their geometrical center. Thus, the center of gravity of an automobile tire or a hollow cube would not be a point on the tire or cube, while the center of gravity of a solid cube would be located at a point of the cube.

When an object is suspended, the center of gravity always lies directly below the point of suspension. This fact can be used to find the center of gravity of an irregularly shaped flat object. If the object is suspended successively from two points and lines are drawn on the object indicating the positions of plumb lines hung from the points of suspension, the two lines will intersect at the center of gravity. A third point of suspension will provide a third line also going through this point as a check.

### The location of the center of gravity

The location of the center of gravity of an object determines whether it will be stable in a given position or not. The more stable an object is, the less likely it is to tip over. As long as the center of gravity is over the base of the object, it will be stable. The lower the center of gravity is, the more one can tip the object and still have the center of gravity remain over the base, causing the object to retum to its original position after it has been displaced. Likewise, a larger base makes an object more stable.

Thus, the cone on the left in the accompanying drawing will be stable because its center of gravity is directly over its base. If it were squashed down so that the area of its base increased and its center of gravity was lower, its stability would be even greater. The cone on the right, however, is unstable and will tip over because its center of gravity does not He above its base.