Demonstrate How to Measure Wind Speed

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 plastic cups extended from four arms. The arms are mounted on a low-resistance 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.