The utter shock of slipping a putt is more than enough of a distraction from the truth. We are so immediately and regrettably forced to accept bogey, while feeling like we deserved the standard, that most of us never really bothered to ask a natural follow-up question:
What the hell just happened?
It turns out that lip-outs are a great lesson in baffling physics, as evidenced by a recent study called “Mechanics of the golf lip-out,” published this week in Royal Society Open Science.
Authors John Hogan and Mate Antali know a lot more about math and physics than anyone wielding a Scotty Cameron, but their recent work analyzed the forces at play as a putt approaches the edge of the hole, hits the edge and sometimes seems to defy gravity.
At its most basic, your putt simply works with different forces, such as speed and angular motion, that determine outcomes based on where the ball enters the hole. Hogan and Antali divided the area of the hole into sections and found that the expected actions of a golf ball at the absolute edge of the hole and the area just below the edge create two different types of lip-outs:
– Edge lip outwards
– Hole lip outwards
Rim lip-outs are much more common, as lip-outs are expected to only occur when the ball’s center of gravity (its center) drops below ground level – i.e. begins to disappear into the pot. They happen of course, but not that often, as we will try to explain below.
Courtesy of Royal Society Open Science
The corner of their study that seems easiest to understand came in the form of these two graphs above. On the left are colored curves showing velocity (y-axis) versus position relative to the edge of the cup (x-axis). Everything above the blue curve is moving at enough speed that the ball loses contact with the edge of the hole and falls into it. Everything below the blue curve maintains contact with the edge – even briefly – and is susceptible to lip-outs.
On the right is a clearer picture for those who have not taken advanced Calculus. You have numbered regions 1, 2, 3 and 4. Putts with Region 2 conditions are expected to fall into the cup – likely because they are not moving at too much pace and/or enter the hole closer to the center of the cup (rather than the rim). But region 3 – higher speed, closer to the edge – would expect an ‘edge lip outward’.
The authors arrive at these results using a spin-free motion, which may make sense since most putts roll end to end near the hole. The study throws up esoteric terms like separatrices, potential energy, dry friction and more, which may not mean much to you, but which brings us to the trickiest part of the map: region 4.
Without spinning, area 4 would almost always result in balls falling into the cup – largely because a standard cup is about 4 inches deep – but because spin can occur when a ball reaches the rim of the cup, it starts spinning And starts to sink in, putts that move under certain conditions can see the ball sink below the horizon of the ground and use that spin to find a zero pitch condition (in this case downswing), causing them to spin around the pot and be quickly ejected back out of the hole.
It is in that area 4 where a ball can experience a “pendulum-like” motion, rolling around the wall of the cup. It’s rare, but it’s what Hogan and Antali have called “golf balls of death”: truly the worst nightmare for golfers trying to score. (To understand it better, see this videoAs dramatic as that name may seem, it is simply a nod to the steady state of motion similarly applied to the famous circus act “the wall of death,” in which motorcyclists speed around seemingly perpendicular to the ground and use angular forces to stay upright in an enclosed environment. (Yes, that means you have a new name for the worst lip-outs you’ve ever seen – just make sure you use it correctly. It won’t happen often!)
Now it’s important to note: a golf course does not exist in a vacuum. These models are determined via standardized shapes on a PDF, not via the contours and architectures that we find outside, with different grass grains, moisture contents and weather conditions. Some of these things can affect a putt’s willingness to fall into the hole or shirk those responsibilities and pop back out. And that’s just Mother Nature. There is always the inner cut of the hard plastic cup in the hole, which is not the case always so perfectly perpendicular to the green.
Unfortunately, whether or not this study has solved the mystery, there is one conclusion we can all agree on: the more your putt moves in the center of the cup, the better. Because the edge teaches hard lessons.
To read the entire study, click here.
#research #explains #symptoms #putts #falling