Football physics: The “impossible” free kick – Erez Garty

Football physics: The “impossible” free kick – Erez Garty

In 1997,
in a game between France and Brazil, a young Brazilian player
named Roberto Carlos set up for a 35 meter free kick. With no direct line to the goal, Carlos decided to attempt
the seemingly impossible. His kick sent the ball flying
wide of the players, but just before going out of bounds,
it hooked to the left and soared into the goal. According to Newton’s first law of motion, an object will move
in the same direction and velocity until a force is applied on it. When Carlos kicked the ball,
he gave it direction and velocity, but what force made the ball swerve and score one of the most magnificent
goals in the history of the sport? The trick was in the spin. Carlos placed his kick
at the lower right corner of the ball, sending it high and to the right,
but also rotating around its axis. The ball started its flight
in an apparently direct route, with air flowing on both sides
and slowing it down. On one side, the air moved in the opposite
direction to the ball’s spin, causing increased pressure, while on the other side, the air moved
in the same direction as the spin, creating an area of lower pressure. That difference made the ball curve
towards the lower pressure zone. This phenomenon is called
the Magnus effect. This type of kick,
often referred to as a banana kick, is attempted regularly, and it is one of the elements
that makes the beautiful game beautiful. But curving the ball
with the precision needed to both bend around the wall
and back into the goal is difficult. Too high and it soars over the goal. Too low and it hits the ground
before curving. Too wide and it never reaches the goal. Not wide enough
and the defenders intercept it. Too slow and it hooks too early,
or not at all. Too fast and it hooks too late. The same physics make it possible to score another
apparently impossible goal, an unassisted corner kick. The Magnus effect was first documented
by Sir Isaac Newton after he noticed it while playing a game
of tennis back in 1670. It also applies to golf balls,
frisbees and baseballs. In every case, the same thing happens. The ball’s spin creates a pressure
differential in the surrounding air flow that curves it
in the direction of the spin. And here’s a question. Could you theoretically
kick a ball hard enough to make it boomerang
all the way around back to you? Sadly, no. Even if the ball didn’t
disintegrate on impact, or hit any obstacles, as the air slowed it, the angle of its deflection
would increase, causing it to spiral into smaller
and smaller circles until finally stopping. And just to get that spiral, you’d have to make the ball spin
over 15 times faster than Carlos’s immortal kick. So good luck with that.

100 thoughts on “Football physics: The “impossible” free kick – Erez Garty

  1. The average footballer won't know this much physics. It maybe is just observation during practise sessions, or a miracle.

  2. In almost any sport involving a ball the Magnus Effect plays its role. Is there any sport other than Cricket that applies the Bernoulli’s Principle?

  3. almost all free kicks have bend in them.. sure not as much as Carlos did but yeah, the concept of the bend is the same in all

  4. Whys this guy call him Carlos? His name is pronounced Roberto Carlos as is printed on the back of his shirt, it’s not shortened to Carlos.

  5. So my question is if we kick the ball in vacuum ..then what will happen? Because then there will be no air to slow down the ball?

  6. You have to know how to play futbol and be good at it to know how a .00something of a second took for RC to hit that ball, while knowing exactly what he was doing

  7. Actually, it's a wrong explanation of the Magnus effect… According to the explanation in the video, ball would go to opposite side, where relative speed between ball and air is higher (and the pressure is lower, according to Bernulli law). But if you consider the layers of air, rotating with ball because of friction between the ball and air, you'll get the correct picture of pressure distribution, causing a curve trajectory

  8. You should do a video on Australian Rules Football (AFL) it's Australia's national sport and we're crazy about it over here but its almost unheard of overseas. The AFL Grand Final is the highest attended club championship event in the world including the super bowl and the players can run upwards of 20kms per game compared to soccer player's 13km. The game is fascinating and unlike any other sport around the world and it's so crazy that its such an institution in Australia but even American sports fanatics have rarely heard of it.

    Check out the video called "What is AFL? Aussie Rules Explained"

  9. The Roberto Carlos goal wasnt a curve ball…but a knuckleball…look at how little the ball spinned…remember, he was known for his POWER…

  10. Here, in Brazil, this kick is named "três dedos" or "three fingers". Bc the three fingers of the feet cause this curve…

  11. Ok read about magnus effect but in reverse mangnus effect why ball curve to high pressure same as in jasprit bhumrha balling tell me

  12. So do with Cricket, as Reverse swing needs the same process. The balls swings on the rough side with the air flow.

  13. Wait I swear Carlos did score from a corner when he was playing in turkey or something. I can't remember but he had curved it from deep in the corner and score too

  14. Its not just the magnus effect.. its also the air pressure inside the ball which moves to the right of the ball at the point of contact with the boot. While the ball is approaching the goal, the air pressure inside the ball shifts from high pressure area to low pressure, creating a movement towards the left. Goodnight.

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