Center of Gravity
Stonehenge and the Trilithion
Trilithion  lab exercise
 
Balance the Bird
I will give you a pattern for the bird in this picture. 
(1) Cut out a cardboard bird from an old photocopy paper box.
(2) Cut a section off the box corner to use as a balance point.
(3) Tape two pennies anywhere on the bird you wish, such that the bird will balance on it tail like in the picture.
The bird

Criteria

To pass the lab your bird must balance on its tail and the trilithion stone must balance again with the same C.O.G., with paper clips or washers added to replace the section you removed.