Center of Gravity

This demonstration shows how to find the center of gravity of an irregular object by hanging it from different points and drawing plumb lines. It also illustrates that the center of gravity moves in a simpler path than other points when the object is spun.

1. Cut out an irregular shape from plywood or stiff cardboard.
2. Drill three small holes near the edges of the shape.
3. Hang the object from one of the holes using a string or hook.
4. Use a plumb line to draw a straight vertical line downward from the point of suspension.
5. Repeat this process from at least one other hole, drawing another plumb line.
6. Mark the point where the plumb lines intersect—this is the center of gravity of the object.
7. On the reverse side, mark the center of gravity with a colored dot, along with several other arbitrary points.
8. Throw the object with a spinning motion and observe the dots. All dots blur, but the center of gravity dot follows a simpler path, showing why it is often used to describe motion.

Centre Of Gravity - Defintion, Examples, Experiment - Educational Videos:

📄 Center of Gravity - UNCO: https://www.unco.edu/nhs/science/pdf/demos/2001_CSC.PDF
🎞️ MIT Physics Demo - Center of Mass Trajectory - Mittechtv: https://www.youtube.com/watch?v=DY3LYQv22qY

• Try different irregular shapes to compare how the center of gravity is located.
• Use transparent plastic instead of wood, so students can see the plumb lines directly.
• Hang the object from three or more points to confirm the accuracy of the center of gravity location.

• Ensure objects are thrown in a safe, open space away from people or breakable items.

• Why must the center of gravity be above the support base for an object to remain balanced?
• Why do the plumb lines always cross at the same point, regardless of where the object is hung?
• Why does the dot at the center of gravity appear steady while other dots blur when the object spins?
• How could this method of finding the center of gravity be useful in real-world applications?