Football is undoubtedly one of the most popular sports in the world, and is one of the biggest businesses around. Despite spending hours on the training ground the commercial side of things is entirely focused on the incidents and highlights of the time played on the pitch. By and large, after the standard training that all players take part in, each player is streamed into perfecting their own set moves.
The free kick can prove to be one of the most decisive incidents to take place in those 90 minutes. It is the dream of many footballers to curl a ball like Roberto Carlos or David Beckham used to in their heyday.
The physics underlying curving a ball involves the initial step of hitting the ball off centre. Once the ball is hit off centre apart from following the normal motion it also starts to rotate as the arrows in the figure shows. As the ball travels forward, air on the left hand side of the ball is travelling in the same direction as its spin and in this way the air gets dragged along with the ball and flows back over its surface.
Air on the right hand side of the ball then starts to move in the opposite direction in relation to the direction of rotation of the ball and so the air separates from the ball instead of getting deflected as what goes on for the left hand side.
In either direction, the air moving around the ball is pressing down on the ball’s surface which creates a force. This force is counteracted by an equal but opposite force upwards of the ball’s surface. This results in the ball pushing the air one way and so the air will apply a force in the other way which is shown in the other figure.
Forces on a moving football.Once the air pushes on the ball it will cause the path to be curved rather than a straight line which is what one would expect. This effect is known as the Magnus effect and takes place in a number of other sports such as baseball.
To make this happen, a player needs the ball to be in exactly the right place so that enough strength can be applied to keep the ball going all the way into the goal post. Even without training for hours on end you can also bend it like a pro!
Did you know…
• The microwave was invented after a researcher walked by a radar tube and a chocolate bar melted in his pocket.
• The human eye blinks an average of 4,200,000 times a year.
• The heaviest human brain ever recorded weighed 2.3 kg.
• No matter its size or thickness, no piece of paper can be folded in half more than seven times.
For more trivia: www.um.edu.mt/think
Sound bites
• Astronomy Night in Dwejra: On May, the Department of Physics and the Institute of Space Sciences and Astronomy (ISSA) of the University of Malta, in collaboration with the Astronomical Society of Malta and Din l-Art Ħelwa, held an astronomy night at Dwejra Tower, Gozo. Over 200 people participated in the very successful event during which the public was invited to gaze at the night sky through a number of telescopes that were set up on site. While the weather was not ideal for observations of deep space objects such as nebulae and galaxies, those present could nonetheless enjoy views of the three bright planets currently in view, namely the red planet Mars, Jupiter and Saturn with its glorious ring system. The event raised awareness about the importance to preserve the dark skies of Dwejra and highlighted to the students present the existing opportunities to further studies in physics and astrophysics at the Department of Physics and the ISSA.
https://www.um.edu.mt/newspoint/events/uomevents/2016/05/astronomynightindwejra
• Finding Hydrogen in distant galaxies: After just 178 hours of observing time, an international team of radio astronomers have successfully pushed the limits of radio astronomy and managed to detect the faint signal emitted by hydrogen gas in a galaxy more than five billion light years away. This is almost double the previous record of such a feat. They did this using the Very Large Array (VLA) of the National Radio Astronomy Observatory in the US which consists of 27 25-metre radio dishes. The result is that they found that this galaxy contained billions of massive young stars and is surrounded by clouds of hydrogen gas.
https://www.sciencedaily.com/releases/2016/06/160601204608.htm