Final answer:
A cup anemometer is used to measure windspeed by counting the number of rotations of the cups attached to a rotating horizontal bar.
Step-by-step explanation:
A cup anemometer is used to measure windspeed. It consists of a rotating horizontal bar with several cups attached to it. As the wind blows, the cups rotate, and the number of rotations in a given time period is used to determine the windspeed. The faster the cups rotate, the higher the windspeed.