Physics of the Carreau
Undoubtedly, the most spectacular shot in pétanque is the carreau,
a violent shot that not only knocks an opposing team's boule out of the game, but actually takes the place
of the boule it displaced.
Have you ever wondered what exactly causes a carreau to happen, rather than just a typical shot, in which both boules end up out of the game? In terms of physics, the incoming boule has to transfer all of its momentum to the target boule.
Here, in the sketch below, is a fairly common situation. The incoming boule strikes the target boule and the ground at about the same time. Note that the extended path of the aggressor boule does not pass through the target boule at all. This will be a successful shot, but not a carreau.
In the next sketch, also a fairly common situation, the target boule has been struck a little high (this type of shot is sometimes called a casquette, or helmet.) Although in this case the path of the incoming boule does pass through the target boule, this will not be a carreau either.
The final sketch shows a true carreau. The point of contact is precisely on the path of the incoming boule. The target boule is struck "dead on," or squarely, and all of the momentum of the incoming boule is transferred.
Seeing how precise the conditions for a carreau are in terms of the physics, it's easy to understand why even the best shooters at the game cannot guarantee a carreau every time.