Month: June 2022

  • Measuring Drag

    Measuring Drag

    After a noticeable rise in the prevalence of home runs beginning in 2015, Major League Baseball commissioned a report that found the increase was caused by a small 3% reduction in drag on the league’s baseballs. When such small differences have a big effect on the game, it’s important to be able to measure a baseball’s drag in flight accurately.

    In the past, that measurement has often been done in a wind tunnel, but the mounting mechanisms used there result in drag measurements that are a little higher than what’s seen from video tracking in actual games. Now researchers have developed a new free-flight method for measuring a baseball’s drag. The drag measurements from their new method are lower than those for wind-tunnel-mounted baseballs and in better agreement with video-based methods. The authors’ method should be adaptable to other sports like cricket and tennis, which will hopefully provide new insight into the subtleties of their aerodynamics. (Image credit: T. Park; research credit: L. Smith and A. Sciacchitano; via Ars Technica; submitted by Kam-Yung Soh)

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    Whistle Physics

    Ever wondered how whistles work? Depending on the type of whistle, there are a few different phenomena in play, but the most fundamental one is the oscillation of a fast-moving air stream. Any small deviation in the air stream can set up a situation where the flow shifts side-to-side, and most whistles use this oscillation to drive the sound they produce.

    Many whistles direct the air flow onto a wedge-shape to strengthen the oscillation; then they have a cavity that amplifies the sound using resonance. Water whistles — which warble in a bird-like way — do the same thing, but the water inside them creates a shape-changing cavity, thereby changing the pitch to create an unsteady, warbling sound. You can see all these whistles and more deconstructed in Steve’s video. (Video and image credit: S. Mould)