Concepts

Centre-of-mass

Overview

An irregular object is suspended from different points. In stable equilibrium, the centre of mass lies below the point of suspension. By drawing a vertical lines through the object in different positions, the centre-of-gravity can be found as the intersection of the lines.

Details

Equipment

• [1] Plexiglas board
• [1] Lab stand
• [1] 90-degree clamp
• [1] Rod with embedded pin
• [1] Plumb bob
  
• [1] Ruler
• [1] Washable marker

Classroom Assembly

1. Clamp the rod and pin to the lab stand.
2. Adjust the height of the rod and pin so that the board can be suspended in all orientations.
   

Script

1. Suspend the object from one point and let it settle to an equilibrium.
2. Draw a vertical line from the point of suspension.
3. Repeat steps 1 and 2 as desired.
   
4. Balance the board with one finger at the intersection of the lines.
   

Additional Resources