Here the pendulums at the North Pole and at Buffalo are both started swinging

along their respective red starting lines. Note the yellow handle of the tool in

the upper right hand corner of the frame. This will serve as a reference marker.

The entire model, including the earth and pendulum is slowly rotated in a

counterclockwise direction. As the model earth rotates, the direction of the

swing is steadily shifting in the clockwise direction with respect to the earth's

surface for both pendulums. This shift is called precession. Can you tell which

one is precessing faster? After a full rotation, as seen by the yellow handle

appearing again in the upper right hand corner, the pendulum at the North Pole

is swinging again along the starting line. The one at Buffalo, however, has not

returned to the starting line yet. In fact, the model must be rotated an additional

amount of over 90 degrees to bring it back to the starting line.