Search the Community
Showing results for tags 'physics'.
Found 3 results
We're in that special hell of rules controversies with the implementation of the new Rules of Golf. There have been some growing pains with the new rules, and that has allowed the golf media to tee off on its favorite target, the USGA. Which, to be fair, can make itself an easy target: https://www.golfdigest.com/story/despite-harsh-words-from-some-tour-pros-usga-pleased-with-roll-out-of-new-rules-of-golf. That aside, I wanted to talk about the "controversy" about the knee-height drop that the Rules now require. Rickie Fowler got a one stroke penalty for dropping from shoulder height this past weekend. Cue the complaining from him: https://golfweek.com/2019/02/22/rickie-fowler-hit-with-one-shot-penalty-for-illegal-drop-at-wgc-mexico-championship/ I can forgive him - he just had a brain fart, probably didn't gain an advantage in this situation, it cost him money. I'm always annoyed when I get a penalty, personally, and it's absolutely never my fault, okay? But cue the pearl clutching from the media: https://www.golf.com/news/2019/02/25/backstopping-pro-tours-under-policed/ I'm here to tell you that this is wrong, and knee-height drops actually make a ton of sense. One of the best things the new Rules do is simplify dropping. Now, all you have to do when dropping is land the ball in the relief area (without touching you or your equipment before hitting the ground) and ensure the ball comes to rest in the relief area. If you don't do this, you have to redrop. Pretty simple. Yes, you have to figure out what your relief area is, but that's pretty simple, too. (For a fuller explanation of this, see Rule 14 and the definitions in the Rules of Golf.) The old rules were much more complex. Specifically, if your ball rolled to one of 9 areas after you dropped it, you had to redrop. For example, if your ball rolled more than 2 club lengths away from where your ball hit the ground, you had to redrop. You had to know all of these 9 areas to know if you needed to redrop or not. So, the new way is simpler, right? Instead of learning 9 different triggers for a redrop, you only have to learn 1. Great! Why am I talking about when you have to redrop? This is why we're dropping from knee height. Generally, under the new Rules, your ball cannot go as far after hitting the ground as it used to without triggering a redrop. Dropping from knee height reduces the chance that a redrop will be necessary. It also means that a ball has less of a chance of embedding in sand when you drop it. It makes a ton of sense, really. Now, you might say, that's all fine, but why not allow dropping a ball from anywhere above knee height? I think you could easily game the rules to be able to place the ball when you really want to by simply dropping from shoulder height instead of knee height. Think about dropping on a side slope, for example. You're much more likely to have to redrop and place if you drop the ball from a higher point. Sure, this is rare, but why take the chance? We're all on the same page, right? Knee-height drops make a lot of sense. (If you want to know more about the changes to dropping, this is an excellent article that talks about this in a bit more detail: https://rulesgeeks.com/2018/12/30-days-of-2019-rules-changes-day-16-procedure-for-dropping-a-ball-in-playing-it-from-a-relief-area/) Now to the point of all of this: golf media, please take 5 minutes to understand the rule before issuing a HAWT TAKE about the rule. The USGA has a one page sheet that explains the rule: http://www.usga.org/content/usga/home-page/rules-hub/rules-modernization/major-changes/new-procedure-for-dropping-a-ball.html. You don't come off very well when you fail to read that. I know it's fun and easy to just mindlessly bash the USGA, but they do get things right. This is one of them. (Oh and by the way, the Rules are actually really good, as a whole. Maybe I'll talk about that in another post later.)
Here's a thread where we can all speculate and share data and thoughts and discuss "theories" and hypotheses… I've shared parts of this in other topics, but I hope to collect everything here, while simultaneously simplifying my position (maybe? hopefully?). I'd previously written a post about how you should almost always leave the flagstick in when you're given the opportunity to (without penalty). It, when you're off the green, tends to help you far more often than it hurts. The flagstick typically slows the ball down and lets it fall into the hole or at least stay closer than it otherwise would have. Then few weeks ago, the USGA and R&A published their proposed rules changes for 2019 (talk about those in the Rules of Golf forum), and one of them was to abolish the two-stroke penalty for striking the flagstick (in the hole) after a stroke from on the putting green. A Dave Pelz study from decades ago backs this up, as does basic physics (collisions lose energy). This, I immediately felt, had the potential to massively change the game of golf. My experience, the research I've read, and talks with others in the sciences and in golf have virtually convinced me of this. The USGA/R&A seem to be ignoring this, saying only "On balance it is expected that there should be no advantage in being able to putt with the unattended flagstick in the hole:". I think they're wrong. The rule is proposed among many to speed up play, and while I admire the USGA's/R&A's desire to speed up play, I'm not even sure it will do that - many have said it may slow play in most instances because where we currently take the flagstick out and put it back in once per hole on most holes, we may find situations where different players prefer the flag in or out and change its status when it is their turn to putt. This topic will not discuss pace of play - just the potential (or real) advantages to be gained. I think these potential advantages will affect two types of putts: Short-medium putts from 4-6', with lesser benefits out to about 10' or 12'. These are putts where players are somewhat or quite likely to hit the hole and, thus, the flagstick. Long putts from 25+ feet. Currently "tap-ins" are about 2' out, but if the first bullet point becomes an issue, and "tap-in" range extends to 4' or 5', the importance of getting your 30-footer to a foot or two diminishes greatly. In this topic, I'd like to explore the pros/cons, the physics, the data, the science, the mentality/psychology… and all of that stuff. I'd like to discuss the theory, the hypotheses, etc. behind this "advantage." This topic isn't about pace of play. It's not about whether we play golf into a "hole" and that this violates some sacred idea or something. It's just about the "advantage." First, some stipulations: There are few regulations on flagsticks. Circular in cross-section, not super dampening like foam or something, not strongly tapered… that's about it. I'm only suggesting a change from 12" past capture speed to about 3' to 4' past capture speed. Do not take me saying "bash it at the stick" or things like that as suggesting that I think players should hit a 5' putt with enough speed to go 10' past the hole. There's some grey area here because greens stimp at different speeds, uphill putts stop closer to the hole than downhill putts traveling the same speed at the hole, etc. Grey areas are unfortunately unavoidable. Players all have different psychologies. Some players will be struggle to do things other players can do more easily. Let's jump right in. Credible arguments for this proposed rule creating an advantage: The flagstick slows the ball by a greater factor than it decreases the time the ball spends suspended over the hole. Unless you have exceptional distance control, effective capture speed can remain about the same. Hitting the ball more firmly allows for a larger margin of error. It also reduces the tendency of a slow-moving putt to "wobble" or be moved off-line due to imperfections. Players, particularly poorer putters, leave a lot of putts from 6' to 15' short. This change would let them be more aggressive. The situations where the flagstick should be removed (it leans too much, it's moving around a lot in the wind) almost never occur. The flagstick offers an aid - it gives the player yet another point or two at which to aim. Credible arguments against there being any advantage: Three putts from short range may increase. Poor putters miss the hole from short range and will miss a lot of the come-backers. Hitting putts faster eliminates the putts that would fall at the outer "edges" of the hole with slower capture speed. These putts don't touch the flagstick, and lip out with faster speeds, but would fall in the "edge" or "side" with slower speeds. Let me take a look at the "pro" list above. 1. The flagstick slows the ball by a greater factor than it decreases the time the ball spends suspended over the hole. Simply put, the ball has to fall 0.84" or so to fall into the hole. Gravity is a constant, so this becomes a matter of time - time which the ball is unsupported and able to fall (another grey area: the ball can be "supported" partially along the "side" of the ball, slowing its descent). But back to the idea of time… Time for an object to fall 0.84 inches is about 0.066 seconds. So what can affect the time it takes? Two things: the speed the ball is traveling (faster = less time), and the route it takes over the hole (going straight across the middle of the hole provides the longest route and the most time to fall) - taking a cord along the edge provides a much shorter route. Many who think they should take the flagstick out when they are chipping from off the green say "the flagstick takes up room in the hole." It does, and so no ball can take a "long" route through the middle of the hole - it will be deflected. So, the question becomes this: how does the flagstick function to affect the time the ball spends unsupported over the hole? It's not as simple as subtracting the diameter of the flagstick from the 4.25", because the ball will contact the flagstick with its outer edge. If you imagine a ball that's hit directly at the flagstick, it will only spend about 2.1" unsupported by the ground - 1.035" from the time the center of the ball goes over the front lip until the front side of the ball hits the stick, and another 1.035" on its way back directly the way it came. The first 1" will be much shorter in time because the ball is moving much more quickly. 2.1" of travel does not afford the ball very much time to drop, and yet… we've all seen a ball rocketing at the flagstick, smack into it dead-center, and fall. In testing I've done, I've rolled balls with as much as 20' past capture speed on a flat portion of a green stimping at about 10 and had them repeatedly fall in to the hole. I shouldn't have to tell you… none of the balls rolled at the same speed went into the hole with the flagstick removed. Thus, the conclusion is simple: the flagstick dampens the speed of the ball by a significantly larger factor than it reduces the distance (and time) that the ball spends in free-fall. A few working physicists have supported this statement in my talks with them, though none have gone beyond preliminary calculations to quantify this, or to measure how advantage declines as you move away from direct hits, though one added that even a "half-ball hit" (he knew I played pool/billiards) should be pretty close to the same math - the ball traveling farther and thus having more time help to offset the less direct impact. Grey areas: 1. Flagsticks differ in their composition. I was using a pretty traditional flagstick, but some courses have wooden flagsticks, metal flagsticks, fiberglass, etc. 2. I'm unsure of how long this holds - It's obvious that a ball that overlaps the flagstick by 0.01" will act almost as if there was no flagstick in there, and regular capture speed rules will basically apply. 2. Unless you have exceptional distance control, effective capture speed can remain about the same. From this thread… … you'll see that a ball putted only 1' past the hole has only the center 2.6" of the hole. At 2' past, the capture width of the hole shrinks quickly to 1.9". Those look like this: Now, obviously that ball rolling 1' past isn't even close to hitting the flagstick, but it's still going to drop (in a pure physics standpoint). The ball hit 2' past is going to hit the flagstick if one was there, but even the edge of the ball isn't passing over the center of the hole (the ball is 1.68" in diameter). (These numbers are part physics, part experimental data, and come from Mark Sweeney.) A ball rolling 3.5' past the hole has an effective capture width of only about 1.2". That looks like this (the flagstick is pictured here simply for continuity): Losing 1.4" is significant (0.7" on both sides) to 0.8" (0.4" on each side) is fairly significant, and that's why, under the current rules, I've suggested people understand and read the capture speed topic, and to strive to deliver the ball with the speed that takes it only a foot or two past the hole. The question is now… what's an effective capture width with the flagstick in the hole and the ball rolling at about 3.5' past the hole? Obviously we need the ball to impact the flagstick enough to slow it down, so let's make an educated guess (based largely on the tests I did last fall, and yes, I know, you're going on a little faith here, but @david_wedzik and I will test thoroughly soon, hopefully this Friday). In my testing, and again I intend to document this fully very soon with Dave, 1.8" provided sufficient flagstick-ball contact to get putts to fall with the flagstick in the hole. "But we've lost 0.8"!", you'll say. And you're right. But remember, that's if you're able to deliver 1' past capture speed. Add just a little and hit your putt with 2' past capture speed and your 2.6" wide target drops down to 1.9" - basically the same width as the picture above. Also, that 0.8" you lost is not the same value. Huh? Consider that PGA Tour players make 77% of their five-foot putts. If we place a bell curve over the effective capture width of the hole, it would look something like this: PGA Tour pros hit the center of the hole more often than they hit the edges of the hole. They don't use whatever size capture width they are given evenly - that's why they make the majority of their putts from 5'. The outer edges - where we're relying on a slowly rolling ball to fall in - don't have the same value as the center of the hole. Bad putters make only about 50% of their putts from 5'. Their bell curve might look like this: Note: the center of the hole is still more important, but the edges are relatively more important. Bad putters hit the center of the hole less often and hit the edges or miss completely more often. If you're still awake at this point, you're correct that 2.6" is wider than 1.8". Even 1.9" is wider than 1.8". If you putt a ball with 3.5' past speed 1.1" off-center, it will miss the flagstick and be traveling too fast to go in. You're correct! But… here's the important thing… With the flagstick in, delivering the ball with 2' past speed within the 1.9" zone or 1' past speed within the 2.6" zone, and the ball will still fall. The flagstick is not hampering your ability to do this at all. There's no negative here - the only negative is if you choose to hit the ball with faster than 2' past capture speed… at which point the flagstick begins to help. At 3' past capture speed, without the flagstick the capture width of the hole shrinks to 1.4". Leaving the flagstick in gains 0.4". It’s insurance in case you hit the ball a little too firmly. If I had to boil down the “is it an advantage” thing to one thing, there it is. This is an important point, so I'm going to hammer it again. If you want to keep putting the way you’re putting now (without the flagstick), do it… but leave the flagstick in, because it will not hurt you if you have good distance control, and WILL help you if you don’t. There's literally no downside here (assuming one of those two conditions - flagstick leaning a LOT or high wind and a jostling flagstick - aren't met). Grey areas: 1. Ball speed vs. roll-out distance on different stimps is not linear - a ball rolling at a speed of x on a stimp 8 green and rolling out 2' past is not rolling 8x/12 if it rolls out 2' on a stimp 12 green. This is why a ball can roll out 3' but still fall in the sides of the hole at Augusta National: the ball is rolling slowly. 2. Players aren't robots. They won't control ball speed to 1' exactly. If they could, and people could read greens perfectly, and greens didn't have imperfections, I'd say take the flagstick out for these putts! 3. Hitting the ball more firmly allows for a larger margin of error. It also reduces the tendency of a slow-moving putt to "wobble" or be moved off-line due to imperfections. Let me address the second part first. In the last 6-12" of a putt, the ball has a tendency to wobble. It's moving more slowly, and minor imperfections can have a large effect on a ball. That's why, though the ideal capture speed is "dead weight" making the hole its full 4.25" wide, it's impractical because you'd leave too many putts short and the ball behaves unpredictably near the hole. Whether you call it the Dave Pelz "lumpy donut" or just the minor variations in the putting surface due to the fact that grass is not a perfectly flat, smooth surface (nor are golf balls, for that matter)… the ball can divert from its path quite a bit in the last foot of its travel. Hitting the ball more firmly makes the path more consistent and thus more predictable. Go ahead… roll a ball on a putting green and watch the last foot of its roll. It'll divert relatively easily, and more so on the slower, bumpier greens many average golfers play. Now, regarding the margin of error… time for more math. Gravity pulls a ball down the hill. If the hill had 0% slope (i.e. dead flat), it would not pull a ball at all. The acceleration due to gravity would be 0 distance/time^s. If the hill had infinite slope (i.e. was a vertical wall), acceleration would be x distance/time^2 (or 9.8m/s^2 if you want to use those units). Any slope between those two points: 0% and infinite %, will be between 0 and x. More slope = more acceleration downhill (i.e. more break). Hitting a ball more firmly means that a ball gets to the destination (the hole) in less time. This lower amount of time means that differences in gravity due to a slight mis-read or a slight error in your start line can be reduced. I'll use some generic units here for distance and time, "d" and "t" because the specific units aren't important. Let's imagine that for a 2% slope, a putt breaks 100d/t^2. A 1% slope will be about 50d/t^2, and a 3% slope about 150d/t^2. Let's imagine two kinds of putts. One takes 10t (time units) to get to the hole (the one we hit firmly), and the other takes 12t to get to the hole. This chart shows how far the ball will deviate due to acceleration (from physics, the ball will travel d = 1/2*a*t^2). I've left the units off just to make the numbers convenient to use, so we could be talking about micrometers per hour squared (though given the units I chose, mm/sec^2 might be relatively close units). Putt Time 1% (50) 2% (100) 3% (150) Delta 10t 2500d 5000d 7500d +/- 2500d 12t 3600d 7200d 10800d +/- 3600d Let's assume the pro reads a putt as 2%. If he plays it firmly, and he's off by 1%, his ball will deviate from the line he read by 2500 distance units (say, 2.5cm). If he's wrong by that same 1%, but hits the ball more softly, and it takes longer to get to the hole… he's going to be off by 3600 distance units (say 3.6cm). A 120% difference (1.2) in time becomes a 144% (1.44) gap in the line. The firmer putt gives our golfer here a larger margin for error in his read. In graphic form, putts would look something like this, where the middle line of each is the proper read (this isn't to scale or the top and bottom blue and red lines would actually be a bit farther apart): If our golfer chooses to hit the ball at 2' past speed (red) or 4' past speed (blue), and 2500d translates to 0.75 inches offline (a make, with the flagstick in, as it is within the 1.8" zone), then his error will send his slower putted ball (red) 1.08" (0.75 * 1.44) offline, which is not within the 1.9" width allowed for a make. He'll miss with the slower putt, and make (comfortably) with the blue putt. In other words, and simplified… when you putt a little bit firmer, a putt has less time to deviate from the line before it reaches the hole if you misread the putt slightly. The faster putt gives you more margin for error in misreading your putt. Good players have known this for a long time. That's why PGA Tour pros rap the ball in the back of the hole (even without the flagstick). That's why you hear "I'll just firm it in and take the break out of it." They're not hitting the ball with 6' past speed… they just hit it with 3' past speed or so, to increase the margin of error on their read. Yes, they're comfortable at hitting their lines to within a small percentage, but as we know already, PGA Tour players make 77% of their putts, and that includes all putts… whether they misread them, hit them too softly or too firmly, etc. So > 77% of the time, they are able to hit their line pretty darn well. Within about half a degree, that number is actually well into the 90% range. 4. Players, particularly poorer putters, leave a lot of putts from 6' to 15' short. This change would let them be more aggressive. Higher handicap golfers leave a lot of their putts short from 6-15'. Just look at this chart, which pretty much matches what @david_wedzik and I have charted: On that chart, you'll see that the 90s golfer leaves over 10% of their 8' putts short of the hole, and nearly 30% of their 15' putts have no chance of going in because they don't even reach the hole! In a chart (there's no real scale here, but you may pretend the vertical line is at 15' or so), these results may look like this, with green representing good golfers, and red representing bad golfers: If leaving the flagstick in and making the come-back putt easier increases the confidence of the two groups to where they can hit their putts with the pace to go just one foot further, we might see a chart that looked more like this: As you can see here, this means 10-20% of their putts that previously came up short will now reach the hole and have a chance to go in. Now, not all of that 20% will go in, but if even half did, it would be a HUGE bonus. Hell, if even a quarter of the 20% went in, bananas! Who wouldn't want to make 5% more putts from 15' (where the 90s shooter only makes 20% right now… despite leaving nearly 30% short of the hole). Ah, but what about an increase in three-putts? Even without the flagstick, 90s shooters three-putt from 12-15' less than 5% of the time. That number is not going to double by adding one foot of pace to the putts, and even if it did double, it would still only break even if just a quarter of those 20% of putts that now reach the hole fall in. Plus, the flagstick will make the come-back putts easier to make. This advice, btw, to make sure you get your 6-15' putts to the hole, applies whether the flagstick is in or out, under the proposed rules or the current rules. This is advice you should follow now, and advice which would only be more relevant and important should this proposed rule actually be put into place in 2019. 5. The situations where the flagstick should be removed (it leans too much, it's moving around a lot in the wind) almost never occur. I debated even leaving this one in here. The first four reasons are pretty strong, IMO. But it's here, and I'll try to be quick about it. The flagstick impedes a ball going in under two very rare circumstances: The flagstick leans toward you so much a ball will not fit between it and the hole. (If it leans toward or away from you a little, it's actually even more advantageous than if the flagstick is straight up and down. So we're only talking about a LOT of lean, and only toward you, in this case.) The flagstick is jostling around in the hole because of high winds or something so it could knock your ball away. (Even this one requires perfect "bad" timing - if the flagstick is jostling away from your ball at the time of impact, your chances of holing the putt are increased even more over a steady flagstick left in.) So, if one was forced to make up some advice about putting with the flagstick in, and they understood ALL of the above five points, they would still conclude that you should leave the flagstick in, even if the advice was not allowed to add the addendum "unless one of these two situations exists." These two situations almost never occur. The ball is almost always helped by the flagstick being in the hole. 6. The flagstick offers an aid - it gives the player yet another point or two at which to aim. I've seen advice on shorter putts about aiming at a small blade of grass at the back of the cup, or where you want the ball to enter the cup, or other sorts of things. Jordan Spieth, for a number of years (he may still do it, I don't know) used to look AT the hole when putting short-ish putts… So, and yes, this is a very small reason or "pro," but that's why it's #6 and only gets three paragraphs: a flagstick can offer another thing at which to aim. It provides visual certainty as to where the middle of the hole is, and players and caddies can say things like "right edge of the stick" or "half a ball outside the stick" or whatever. For straight-ish putts, the flagstick is in the middle of the hole, and obviously offers a nice aiming point. Never mind that the flagstick shadow can be quite helpful in aiming. There have been a number of times when teaching AimPoint classes or playing by myself that where the flagstick shadow was on the green, on the edge of the hole, etc. was helpful in offering an aim point for my putting. In summary… Here's the deal… With the flag out, at 1' past, the capture width of a hole is 2.6". At 2' past, it's 1.9". At 3', it's 1.4", and at 4' it's 0.9". With the flag in, at 1' past, the capture width of a hole is 2.6". At 2' past, it's 1.9". At 3', it's 1.85", and at 4' it's 1.8". At 5', it's 1.7". For good putters, who can reasonably control their start lines to +/- about 0.9" at the hole, adding a little pace to their short-ish putts can remove some wobble, provide more margin for error on their reads, and allow them to make more putts. The flagstick offers a significant advantage. For poor putters… even if you just keep putting the same way you are now (except please take our advice on not leaving so many makeable putts short - hit them just a little harder), leaving the flagstick in can not hurt you, and on the putts you "goose" a little, can only really help you. Maybe you're confident from 4' at hitting the flagstick, but not from 6'. Or from 3' but not even 5'. Either way, it can't hurt you, and can only help you… just not as much as it can help a good putter. The "cons" above assume everyone's going to be smacking the ball at the hole so it runs out several feet farther than it does now. The cons above can be completely eliminated if everyone just putts as they do now, and recognizes situations where hitting the ball a bit firmer and using the flagstick is advantageous. There's no downside here. Not if you're smart enough to take the flagstick out (or re-center it in the hole) when it's leaning 30° toward you… And that is why I'm opposed to this rule. It's only really an advantage. The USGA and R&A are wrong that it will offer no advantage, and in fact, I would imagine that it will offer the biggest advantage to the better players. Despite the fact that, say, they make 77% of their five-footers while the 90s golfer makes 50%, and thus have a smaller range to improve (23% versus 50%), I still imagine, if this rule passed and was instituted, that we might see that 77% go up by a larger percentage than we see the 50% increase. In truly closing, look, this post was composed over three days, and multiple hours, and many, many stops and starts. I retain the right to fix any errors, tweak my conclusion, and otherwise to edit. For anything that affects the actual points and isn't just grammatical or spelling in nature, I'll note it publicly in this topic discussion. I encourage everyone to read this over, and to consider what I've said, and to discuss. I think this is important, and I think the USGA/R&A are risking seriously altering the game if this proposed rule sticks. I'm fighting this fight because I care about golf, and I do not think that we should be playing into anything but a hole, ultimately, for the shots that are more likely to go in - putts from on the green. I'd support a rule that let you keep the flagstick in the hole for putts outside of a certain distance, like 20', because for those I could perhaps be swayed by pace of play arguments… but I don't think such a rule will exist because then we'd have to be able to measure 20' or 7 yards or some distance pretty accurately (and often quickly).
http://www.dstgolf.com/optimise-golf-swing/how-dst-golf-clubs-work You'll notice that everything in that description talks about how the shaft appears, or how a line appears, so that you set up properly. In essence, everything - the shaft being bent, the wide sole with a specific bounce, and the line near the hosel - is geared toward one thing: to get the handle forward at setup. As you can see, I've done that here in two swings: So far so good, right? I added a white line so that you can see the curve in the shaft. I will tell you that it appears to be more severe at setup. Unfortunately, the simple physics of swinging a golf club are that the heavy part - the mass at the end of the stick - wants to line up and form a straight line pointing at the center of the arc on which it's being swung. Consider tying a small weight to the end of a string. Swing it around: over your head, in front of you, beside you, on an angle… and you'll notice that the weight pulls the string tight. Simple physics. So, whether you flip or not, the weight on the end of the string (the clubhead) pulls the string (the shaft) taut. On the left, my weight is moving back and I'm throwing or flipping the clubhead. On the left, a "good" swing. This renders the DST a "visual" training aid only. It fails at doing much more than your clubs do already at letting you know whether you flipped at the ball or not. Here are the videos: