'(<a href="http://www.j-archive.com/media/2011-01-19_J_06.wmv">Kelly of the Clue Crew rolls two ping-pong balls on the table.</a>)  The tack in a ping-pong ball shifts this 3-word directional term from the middle to the side, affecting its roll'
the center of gravity
BASIC SCIENCE: The tack in a ping-pong ball shifts this 3-word directional term from the middle to the side, affecting its roll
The tack in a ping-pong ball shifts this 3-word directional term from the middle to the side, affecting its roll
The tack in a ping-pong ball shifts this 3-word directional term from the middle to the side, affecting its roll
BASIC SCIENCE
the center of gravity
BASIC SCIENCE