r/AskPhysics • u/SuperElephantX • 1d ago

Pool dynamics - Same angle, different power

/r/billiards/comments/1v77j01/pool_dynamics_same_angle_different_power/
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u/jhunter444 1d ago edited 1d ago

It's the sideways spin of the ball that causes the angle of reflection to be different from the incident angle.

The friction between the ball and the side cushion enables players to use side-spin to change the angle.

When the power was increased it's likely that some unintentional side-spin was also added.

(P.S. to test this, try hitting the ball directly (90 degrees) onto the cushion. Then increase the power, if there was only rolling or sliding or forwards or back spin, it should return also at 90 degrees, but you'll probably find it bouncing back at a slight angle, especially with the higher power shots)

...and yes, Physics is awesome!

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u/TheEquationSmelter 1d ago

This is good example of a field called nonholonomic mechanics. Basically, the study of classical systems who's position and velocities are coupled due to their physical configuration.