I am doing my physics PBL demonstration on balancing. I chose this topic because I am very interested in how things balance and the center of gravity. In my demonstration i will be balancing a fork and a spoon on the rim of a glass using only a toothpick to rest on it. The center of gravity of any object is the point about which you can balance the object as if all the masses were concentrated or gathered at this point. In other words, it's the point at which the object balances from left to right, front and back, and top and bottom. In this balancing fork act, the center of gravity is right below the spot where the toothpick rests on the rim of the glass. This actually puts the center of gravity directly below the point where the toothpick is balanced (called the pivot point). Here's where it gets really strange: the center of gravity, where the forks balance front and back, left and right, top and bottom, is actually hanging in mid-air.In physics, the center of mass of a distribution of mass in space is the unique point where the weighted relative position of the distributed mass sums to zero. The distribution of mass is balanced around the center of mass and the average of the weighted position coordinates of the distributed mass defines its coordinates. Calculations in mechanics are often simplified when formulated with respect to the center of mass.
In the case of a single rigid body, the center of mass is fixed in relation to the body, and if the body has uniform density, it will be located at the centroid. The center of mass may be located outside the physical body, as is sometimes the case for hollow or open-shaped objects, such as a horseshoe. In the case of a distribution of separate bodies, such as the planets of the Solar System, the center of mass may not correspond to the position of any individual member of the system.
The center of mass is a useful reference point for calculations in mechanics that involve masses distributed in space, such as the linear and angular momentum of planetary bodies and rigid body dynamics. In orbital mechanics, the equations of motion of planets are formulated as point masses located at the centers of mass. The center of mass frame is an inertial frame in which the center of mass of a system is at rest with respect to the origin of the coordinate system.