Using the center of gravity, how do we tell when the object has reached its tipping point?

• A. Right before the center of gravity passes past the base of the object
• B. Right after the center of gravity passes past the base of the object
• C. When the center of gravity stays at the same height
• D. When the center of gravity moves upwards

Answer: (B)

Stability depends on where the weight acts relative to the base of support. When the center of gravity’s vertical line stays inside the base, there’s a restoring moment that keeps the object upright. As the object tilts and the center of gravity moves toward the edge, the vertical line shifts toward the boundary. The tipping point happens as soon as the center of gravity passes past the edge of the base, because beyond that there’s no longer enough support to keep it upright and it will rotate and fall. Changes in vertical height of the center of gravity don’t determine tipping by themselves, and simply moving upward isn’t enough to cause tipping. So tipping begins right after the center of gravity passes past the base.