It may seem like I have balls on the brain if my last couple of posts are any indication. Balls are such a big part of sport and Sports Engineers are fascinated by the way they behave as they bounce on the ground and fly through the air.

I’ve seen two amazing videos recently which exhibit the way in which balls can still baffle us.

Rugby, the penalty of wind

The video below shows a Rugby player taking a penalty in what the Irish tourist board might describe as ‘a slight breeze’. Be sure to watch from all angles to get a good idea of what’s going on.

The back-spin naturally added to a rugby ball from a penalty kick generates lift which increases the distance travelled. The gale force wind in this case greatly increases the magnitude of the lift so that the ball seems to float in the air. Combine this with the huge drag forces and the ball nearly ends up back where it was kicked from!

Tennis, the ultimate drop shot

A colleague in the ITF showed me this video, and many of you may have seen it already. I’ve included a version with a Discovery channel commentary for a little more insight.

The ITF have done a massive amount of work on benchmarking surface behaviour, the bounce and spin of a playing surface can greatly affect the nature of the game. This video just goes to show how many factors there are governing the seemingly simple mechanism of a bounce. In this case it seems that a bubble in the court’s surface is absorbing almost all of the kinetic energy of the ball, stopping it dead.

As busy as we are at the Centre for Sports Engineering Research, we’ll try and post up interesting and exciting sports engineering videos as we come across them. You never know we may even get round to making some of our own in time.

Simon Choppin