How do you measure the speed of something
you can’t see? This model shows students
how to compute wind velocity by counting the
rotations of four metal cups extended from
four arms. The arms are mounted on a lowresistance
axis that rests on hard steel jewel
bearings. Even a mild breeze, as gentle as 2
mph, will start the arms and cups moving. Size:
6 1/2”H x 8 1/2” dia.