# A convincing calculation: ten soccer players ensure excitement

##### March 13, 2006

One ball, two goals and 22 soccer players – and the game can begin. But why are there ten players of one team on the field and no more or less? This is what Metin Tolan, professor for experimental physics at the University of Dortmund (Germany), tries to get to the bottom of in view of the World Cup.

No matter whether it’s the German professional soccer league or a friendly game - the important thing is the excitement. A simple calculation shows that the number of players is of great importance.

A regular field with 7,000 square meters naturally has room for more than 20 players. But when they stand too close together, the ball whirls around like a pinball and the field turns into an amateur soccer field. Here nobody can speak of controlled ball possession anymore. When there is too much distance between the players, the opposite phenomenon can be observed: the adversarial team takes too long to run after the ball and the game can not be gripping.

“The decisive factor is the time a player needs to catch a passed ball and to continue playing and the time the opponent needs to get the ball back”, Metin Tolan explains. The physicist has calculated that each of these reactions takes about three seconds. “The distance between the players is optimal when both sides are more or less equal. Then the game is smooth - and exciting”. And that is exactly the case when, besides the goal keepers, there are 20 players on the field.

Further numbers illustrate the dynamics of the popular sport: With 18 km/h the professionals cover an average of five meters per second on the field. Additionally Tolan found out that a ball can fly faster than the foot that hits it. The elasticity number of the ball gives it even more drive.

Source: Universitaet Dortmund

Explore further: Student researchers build table-football robot

## Related Stories

#### Student researchers build table-football robot

August 11, 2016

ls in table football. The next step will be to program the robot with some strategy and organise a competition among robots.

#### What's troubling athletes arriving in Rio? No 'Pokemon Go'

July 30, 2016

So the plumbing and electricity in the athletes' village took several days to fix. Who cares?

#### How we evolved a winning strategy for the RoboCup competition by imitating nature

August 15, 2016

"In football everything is complicated by the presence of the opposite team." This observation by the French philosopher Jean-Paul Sartre has been cited in multiple contexts, ranging from tactical planning in team sports, ...

#### Does practice make an Olympian? Not by itself

July 28, 2016

We've all heard that "practice makes perfect," or at least that "perfect practice makes perfect." Is this true?

#### Researcher analyzes acoustic properties of golf club drivers

August 10, 2016

Two years ago, acoustics graduate student Peter Kerrian started playing golf after years of watching PGA tournaments on television. Now, his hobby has provided him an opportunity to help understand the design of golf clubs.

#### The straight story: Bow and arrow advances lift other sports

August 7, 2016

Hall of Famer Wayne Gretzky's slap shot was always precise and straight as an arrow. Give archery an assist for that.

## Recommended for you

#### LiH mediates low-temperature ammonia synthesis

August 24, 2016

Nearly half of the world's population is fed by industrial N2 fixation, i. e., the Harbor-Bosch process. Although exergonic in nature, NH3 synthesis from N2 and H2 catalyzed by the fused Fe has to be conducted at elevated ...

#### Selecting the right house plant could improve indoor air

August 24, 2016

Indoor air pollution is an important environmental threat to human health, leading to symptoms of "sick building syndrome." But researchers report that surrounding oneself with certain house plants could combat the potentially ...

#### Nutrition matters: Stress from migratory beekeeping may be eased by access to food

August 24, 2016

In the first large-scale and comprehensive study on the impacts of transporting honey bees to pollinate various crops, research from North Carolina State University shows that travel can adversely affect bee health and lifespan. ...

#### A new path for killing pathogenic bacteria

August 24, 2016

Bacteria that cause tuberculosis, leprosy and other diseases, survive by switching between two different types of metabolism. EPFL scientists have now discovered that this switch is controlled by a mechanism that constantly ...

#### Engineers discover a high-speed nano-avalanche

August 24, 2016

Charles McLaren, a doctoral student in materials science and engineering at Lehigh University, arrived last fall for his semester of research at the University of Marburg in Germany with his language skills significantly ...

#### Bags don't fly free: Charges have boosted airlines' departure performances, study finds

August 24, 2016

When most major airlines began charging flyers for checked bags in 2008, travelers grumbled. Southwest Airlines—one of the most successfully run airlines in history—even resisted and seized a new marketing slogan "bags ...