Golf balls of death: Scientists explain mystery golfing phenomenon

London (dpa) – Two scientists have turned their mathematical and engineering skills to the cruellest phenomenon of golf, offering an explanation for the mystery of why golf balls sometimes appear to fall into a hole only to pop straight back out again. According to a study by Stephen Hogan of the University of Bristol and Máté Antali of Széchenyi István University, published on Wednesday in the journal Royal Society Open Science, the phenomenon applies not only to golf but also to mini golf. "Half of golf is fun, the other half is putting," the authors quote golf writer Peter Dobereiner as saying, illustrating the frustration of final putts on the green. They have now developed two mechanical explanations for what golfers call a lip-out, but what has also been called a roll-out, the golfer’s dilemma, the golf ball paradox, golf balls of death and the golfer's curse. The team presents a mechanical model for a rim lip-out and one for a hole lip-out. In a rim lip-out, the golf ball’s centre of mass does not fall below the level of the green. The ball rolls towards the hole, but its centre does not move towards the hole’s centre. It therefore reaches the rim at an angle, and the inward tilt into the hole is not great enough to overcome the momentum of the rolling motion. The ball is slightly deflected, but the roll remains dominant. In a hole lip-out, the golf ball’s centre of mass drops lower. Here, the ball rotates around its own axis. More precisely, it has a spin component in a direction different from the roll. In this case, the ball can disappear completely below the rim and then, driven by its spin, turn itself back out of the hole. This only works if the ball does not touch the bottom, because that contact would disrupt the motion and the ball would remain in the hole. The authors add that there is at least one further kind of lip-out they did not analyse in detail, one they call "ballistic lip outs." "These can occur when the golf ball impacts the opposite rim, rolls along it and then returns to the green." The two researchers were also part of a 2021 author group that described in detail the physics of a ball rolling along the rim of a basketball hoop. The following information is not intended for publication dpa fm zlw yyzz n1 hu

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