# Physics can improve your football

##### May 22, 2006

As the World Cup draws closer and football fever starts to take over, physicist Nick Linthorne has found out how players like Gary Neville can achieve the perfect long throw-in, which could be crucial in setting up a goal for the England squad. An article, A new angle on throwing, in the June edition of Physics World, describes how the physics of projectiles can be used to calculate the optimum angle at which a ball needs to be released to achieve the longest possible throw-in. The article describes how the optimum angle is much less than physicists previously believed.

When a player takes a long throw-in, they want the ball to travel as far as possible. The distance a ball travels when it is thrown depends on both the speed at which it is released and the launch angle. According to the laws of basic physics, a simple projectile will travel furthest when launched at an angle of 45 degrees.

However, this approach assumes that the launch speed is independent of the launch angle. New research, however, has found out that this is not true in practice, as when most footballers take a throw-in they use shallower angles nearer 30 degrees. This is because the muscles in a player’s arms and back allow more horizontal than vertical force to be exerted on the ball when it is released.

Dr Nick Linthorne, a physics lecturer and researcher at Brunel University, and his student David Everett came to this conclusion after taking video footage of two players performing throw-ins at a variety of angles. They then used computer software to measure the different ball speeds and angles in the video.

Dr Linthorne said “To calculate the optimum angle at which to launch the ball, we first derived an expression from the video data, linking the release speed to the release angle. This expression for release speed was then substituted into the physics equation for the range of a projectile. By plotting a graph for the range versus several angles, we were able to calculate the optimum angle of release to be 30 degrees. Of course the angle will vary for each player, as they have different strengths, but for most players the optimum launch angle is calculated to be between 25 and 30 degrees, which agrees with what we see from players on the pitch.”

How far a ball travels when a player takes a throw-in depends on other factors such as the player’s limb lengths and muscle strengths and most players use trial and error to work out the best angle for them. This formula explains the physics behind what they practise and why it works. No doubt there will be many other moves seen on the pitch this summer such as curving free kicks that can also be explained by physics.

Source: Institute of Physics

Explore further: Get ready to build! Hands-on toys that teach are hot

## Related Stories

#### Get ready to build! Hands-on toys that teach are hot

November 22, 2016

Toys that teach aren't a new thing, but a growing number are calling for kids to build with blocks, circuits or everyday items before reaching for a tablet screen.

#### Team ahead of the 'curve' in magnetic study

September 21, 2016

When a baseball pitcher uncorks a nasty curveball, the spinning motion of the ball forces air to flow around it at different speeds, causing the ball to "break" in one direction.

#### Some brains are blind to moving objects

September 28, 2016

As many as half of people are blind to motion in some part of their field of vision, but the deficit doesn't have anything to do with the eyes.

#### Great expectations from fewer collisions

September 22, 2016

Usually, the motto of the LHC is 'maximum luminosity' (in other words, as many collisions as possible).

#### Breaking ball too good to be true (w/ Video)

October 13, 2010

(PhysOrg.com) -- Curveballs curve and fastballs go really fast, but new research suggests that no pitcher can make a curveball "break" or a fastball "rise."

#### How does an outfielder know where to run for a fly ball?

January 21, 2010

(PhysOrg.com) -- Faced with a fly ball soaring deep into center field during the 1954 World Series, New York Giants center fielder Willie Mays turned his back on the ball, ran straight to the center field fence and caught ...

## Recommended for you

#### Photonic crystal enhanced microscope sheds light on wound healing and cancer metastasis

December 7, 2016

University of Illinois Electrical & Computer Engineering and Bioengineering Professor Brian Cunningham's Nano Sensors group has invented a novel live-cell imaging method that could someday help biologists better understand ...

#### Uncovering the secrets of water and ice as materials

December 7, 2016

Water is vital to life on Earth and its importance simply can't be overstated—it's also deeply rooted within our conscience that there's something extremely special about it. Yet, from a scientific point of view, much remains ...

#### Physicists develop technique to save more lives by vaccinating fewer people

December 7, 2016

Scientists at the University of Aberdeen have developed a mathematical method to prevent epidemics by vaccinating fewer people than ever before.

#### Blocks of ice demonstrate levitated and directed motion

December 7, 2016

Resembling the Leidenfrost effect seen in rapidly boiling water droplets, a disk of ice becomes highly mobile due to a levitating layer of water between it and the smooth surface on which it rests and melts. The otherwise ...

#### The case for co-decaying dark matter

December 5, 2016

(Phys.org)—There isn't as much dark matter around today as there used to be. According to one of the most popular models of dark matter, the universe contained much more dark matter early on when the temperature was hotter. ...

#### Tunneling holds key to high-speed modulation of transistor and laser development

December 5, 2016

In 2004, electrical engineering pioneers Nick Holonyak, Jr. and Milton Feng at the University of Illinois invented the transistor laser—a three-port device that incorporated quantum-wells in the base and an optical cavity—increasing ...