Center of Gravity of irregular objects

From WikiEducator
Jump to: navigation, search

Concepts to investigate:

Geometric center,Internal center of mass,external center of mass.


Nails or pencils,cardboard,scissors,coat hanger and horseshoe.

Principles and procedures

How can we determine the C.G of an irregularly shaped object such as a piece of cardboard or coat hanger?

From a cardboard box,cut an irregular possible and use a nail or pencil to punch 3 holes in the perimeter of the cardboard. Slightly enlarge these holes so the cardboard can rotate freely. Place a nail or pencil from one hole and hang a weight from it with a piece of string. Swing the cardboard and when it comes to rest  ,draw a pencil line on the cardboard showing the position of the string. The cardboard swings back and forth as a a pendulum until the center of mass comes to rest directly below the point of support. This position represents the state of least energy and all bodies move towards a position of minimal energy. Repeat using the other two holes. The intersection of the three lines is the Center of Gravity(C.G). Attempt to balance the card at this point,It should balance.

What is the fewest number of lines necessary to locate the center?

To determine the center of mass for the coat hanger or horseshoe, tape a piece of paper in the middle and repeat the procedure as described above,drawing the lines on the piece of paper.

Where is the the center of mass?


(1) Will the position of the center of mass of an object ever be different from its  center of gravity?

(2) Name several different objects in which its C.G lie outside the body?