Hacker News Reader

Comment by nemo44x | Hacker News Reader

Is this because of imperfections in the fabric? Golf has a similar situation where if you use a machine to roll a ball on a perfect line and speed, sometimes it won’t go in. This is because of imperfections in the gradient and that grass changes constantly as it slowly grows and bends towards light, etc.

Wow now that’s a tangent to a tangent!

View on HN

There was still ongoing dispute between pool and snooker players whether playing side spin on white ball affects angle of the object ball hit by the white (ignoring deflection, just the spin transfer).

In real life it depends on the tables bed, banks, cloth (different material, speed, whether it's clean or dirty, it's 'mileage', air temperature and humidity...), balls, cue and of course human factor.

seems like you could test this. simply line up a very easy (and repeatable) combination shot with the two object balls really close to each other and vary the contact and spin as needed. the closer the cue ball to the first object ball will mean that you could minimise the impact of deflection. have to try it next time I'm near a pool table!

I've always assumed that deflection, swerve and throw were a given but sounds like they're debating the "throw" part?

Not imperfections, the fabric itself. If the balls were on a frictionless surface, their movement would be completely different, they would barely spin. Much of their movement is caused by their interaction with the fabric. But that is very hard to model from Newton's laws of motion.

Reply on news.ycombinator.com