First, we have to intertwine the forks with the toothpick and leave them in balance at the edge of the glass. The balance is obtained because the centre of the gravity is under the support point.
What would happen if we burnt the edge of the toothpick that is inside the glass?
A part of the toothpick is burnt, but the flame is put out when it’s at the edge of the glass and the balance of the forks is kept.
The loss of volume of the toothpick that is burnt, doesn’t affect to the centre of the gravity
by Teresa and Ángela