WEBVTT

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In 1997, 
in a game between France and Brazil,

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a young Brazilian player
named Roberto Carlos

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set up for a 35 meter free kick.

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With no direct line to the goal,


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Carlos decided to attempt 
the seemingly impossible.

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His kick sent the ball flying
wide of the players,

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but just before going out of bounds,
it hooked to the left

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and soared into the goal.

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According to Newton's first law of motion,

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an object will move 
in the same direction and velocity

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until a force is applied on it.

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When Carlos kicked the ball,
he gave it direction and velocity,

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but what force made the ball swerve

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and score one of the most magnificent 
goals in the history of the sport?

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The trick was in the spin.

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Carlos placed his kick
at the lower right corner of the ball,

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sending it high and to the right,
but also rotating around its axis.

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The ball started its flight
in an apparently direct route,

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with air flowing on both sides
and slowing it down.

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On one side, the air moved in the opposite
direction to the ball's spin,

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causing increased pressure,

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while on the other side, the air moved
in the same direction as the spin,

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creating an area of lower pressure.

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That difference made the ball curve
towards the lower pressure zone.

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This phenomenon is called
the Magnus effect.

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This type of kick, 
often referred to as a banana kick,

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is attempted regularly,

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and it is one of the elements
that makes the beautiful game beautiful.

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But curving the ball 
with the precision needed

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to both bend around the wall
and back into the goal is difficult.

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Too high and it soars over the goal.

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Too low and it hits the ground 
before curving.

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Too wide and it never reaches the goal.

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Not wide enough 
and the defenders intercept it.

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Too slow and it hooks too early,
or not at all.

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Too fast and it hooks too late.

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The same physics make it possible

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to score another 
apparently impossible goal,

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an unassisted corner kick.

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The Magnus effect was first documented
by Sir Isaac Newton

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after he noticed it while playing a game
of tennis back in 1670.

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It also applies to golf balls,
frisbees and baseballs.

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In every case, the same thing happens.

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The ball's spin creates a pressure 
differential in the surrounding air flow

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that curves it 
in the direction of the spin.

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And here's a question.

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Could you theoretically 
kick a ball hard enough

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to make it boomerang 
all the way around back to you?

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Sadly, no.

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Even if the ball didn't 
disintegrate on impact,

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or hit any obstacles,

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as the air slowed it,

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the angle of its deflection 
would increase,

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causing it to spiral into smaller 
and smaller circles

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until finally stopping.

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And just to get that spiral,

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you'd have to make the ball spin
over 15 times faster

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than Carlos's immortal kick.

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So good luck with that.