A wine glass containing is less stable?

The center of gravity of a wine glass containing liquid is located above the base of the glass. As more liquid is added to the glass, the center of gravity rises, making the glass more top-heavy and less stable.

This is why it is important to be careful when pouring wine into a glass, especially if the glass is already full. If the glass is tilted too far, the center of gravity will shift too far to one side and the glass will tip over.