B76. Center of Mass of an Arbitrary Object

DYNAMICS - Center of Mass

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A flat, irregularly-shaped piece of masonite is hung from different holes on separate occasions. Each time, a ruler is used to mark the a vertical line pssing through the hole. The point at which these lines intersect is the center of mass. There are three other shapes that can be used; an equilateral triangle, a sector of a circle, and a semicircle.

Center of Mass Demonstration Kit:

Finding the center of mass of a circle or square is simple. But oddly shaped objects have unusual centers of mass. You might want to ask students where they think a center of mass will fall, then show them the answer using our Center of Mass Demonstration Kit. We give you four pre-cut shapes: an equilateral triangle, a sector of a circle, a semicircle, and an irregular shape. The center of mass of the last is located outside of its body altogether. Their large black forms will help all your students see them clearly.

The set comes with a plumb line and bob and chalk. To show the center of mass of the equilateral triangle, for example, you can hang it from a predrilled hole in one of its corners. The chalk line is also hung from the same point, then snapped against the figure. You repeat this process, hanging the triangle up by each of its corners in turn. The center of mass is obvious as the point where three lines intersect. A special suspension adapter is also included for easy hanging.

List of Parts:
1. Odd-shaped wood sheet
2. 4’ rod; 6’ rod
3. Table clamp
4. Right angle clamp

Assembly:
1. Clamp long rod to table
2. Clamp short rod to rod as shown
3. Hang wood piece

Operation:
1. Hang wood piece from one hole
2. Hold ruler vertically; draw chalk line
3. Hang piece from different hole
4. Draw chalk line, as before

Location: Room 4-309B, Wall; Shelf D2