Scientists investigate why golf balls sometimes bounce out of the hole after seemingly sinking.
Every golfer has experienced the frustration: a perfectly aimed putt rolls toward the hole, appears to drop in—and then inexplicably bounces back out. Now, a new study sheds light on this puzzling phenomenon, offering a scientific explanation that may not ease the pain, but at least provides some clarity.
Golf is a global sport with millions of passionate players. The mystery of the ‘lip out’—when a ball rolls around or out of the hole—is a shared experience. Researchers from the University of Bristol in the UK and Széchenyi István University in Hungary have taken a closer look at the physics behind this occurrence, publishing their findings in the journal Royal Society Open Science.
Why do golf balls bounce out of the hole?
The study identifies two main reasons for the bounce-out: the tilt of the ball and its spin. When a ball approaches the hole at an angle, its center of mass may not align with the hole’s center. If the tilt isn’t steep enough to overcome the ball’s rolling momentum, it veers off course, grazing the edge and rolling away—this is known as a ‘rim lip out.’
Even more frustrating is the ‘hole lip out,’ where the ball seems to fall into the hole but spins back out. This happens when the ball has a rotational spin in a different direction than its rolling path. If the ball hasn’t yet touched the bottom of the hole, the spin can cause it to climb back up and out, defying expectations.
Physics meets putting frustration
Lead researchers Stephen Hogan and Máté Antali are no strangers to ball dynamics. Their previous work analyzed basketball behavior at the rim. In this golf study, they applied similar physics principles to model two types of lip outs. Their findings help explain why even well-aimed putts can fail in seemingly impossible ways.
One variant of the lip out remains unexplained: when the ball hits one edge of the hole, rolls along the opposite rim, and either drops in or returns to the green. The researchers acknowledge this as a future area of study.
While the science may not eliminate the sting of a missed putt, it offers golfers a deeper understanding of the forces at play. And perhaps, a little less frustration the next time the ball refuses to stay in the cup.