• Question: why does spinning a ball make it curve?

    Asked by leeromecarlisleunited to Helen, Jenni, Mark, Martin, Stu on 20 Jun 2011.
    • Photo: Stuart Mourton

      Stuart Mourton answered on 20 Jun 2011:

      It’s to do with the difference in air resistance the rotating ball produces on either side of it. On one side the ball will be spinning in the same direction as the wind passing over it, whilst the other side will be spinning against the wind. The ball will curve towards the side with lower resistance, as it’s easier for it to travel through lower resistance air.
      This is how footballers bend free kicks over and around defensive walls and how baseball pitchers get lots of swerve and dip on their pitches.

    • Photo: Jenni Tilley

      Jenni Tilley answered on 20 Jun 2011:

      It’s all to do with newton’s third law (For every action there is an opposing reaction) and how the air flows over and around the ball.

      This website explains it brilliantly:
      http://www.exploratorium.edu/baseball/curve.html

Comments