Ball flight laws and off-center hits

[Cornbread]

The only thing that can have topspin is a ball that's topped. Hooks don't have ANY topspin. None. Zero.

I understand much of your logic your latest reply, (and for the record I understand physicis far more than 95% of the polulation), thus I'm an Engineer.

Your logic is true in say 98% of the cases of a golf ball in flight, however much like a curveball or diveball in baseball, a Golf Ball CAN have topspin and not be a topped wormburner, or a ball that makes ground contact say 4" in front of the Tee from which it was struck. Obviously this may happen easier with say a 7 degree driver vs a 12 degree, but it can happen. Add to this the fact that a balls spin rate decreases with time / distance traveled so its quite feasable that some balls in flight just prior to landing have no remaining back spin (or any spin). Will it convert to forward spin, or topspin... of course not. How many of us as a teenager playing and infield position during a baseball or softball game had to deal with a funky struck knuckleball coming at us. That was a ball without spin of any kind.

[zeg]

Your logic is true in say 98% of the cases of a golf ball in flight, however much like a curveball or diveball in baseball, a Golf Ball CAN have topspin and not be a topped wormburner, or a ball that makes ground contact say 4" in front of the Tee from which it was struck.

It is physically possible for a ball struck by the face of the club to have topspin, yes. Akin to the left-right ballflight laws, that just means that the clubhead path is upward at a steeper angle than the effect loft of the club at impact.

HOWEVER, no one would ever mistake a ball struck in that fashion for a properly hit ball. With topspin it will flare and drop with almost no distance. Even a knuckleball-struck golf ball would be a miserable shot. It's not something anyone would ever bother describing (well, maybe Phil Mickelson has some trick shot from a bunker that uses it, but that's different )

[Deryck Griffith]

In general Hooks do have more topspin than Fades or Slices. But that is not a general statement that can be applied in every case. THe particular spin applied at impact differs, creating different types of hooks and fades. Some have mostly sidespin, some have mostly topspin or backspin.

If a hook had top spin, it would drop out of the air like a curveball....

[iacas]

Your logic is true in say 98% of the cases of a golf ball in flight, however much like a curveball or diveball in baseball, a Golf Ball CAN have topspin and not be a topped wormburner, or a ball that makes ground contact say 4" in front of the Tee from which it was struck.

The number is far, far, far, far, far closer to 100%. It's nowhere near (relatively) 98%.

As zeg said, any such instance of a ball hit like that is NOT a "properly hit golf ball." I don't care for the way you've changed your tune, either. You originally said "hooks have more topspin than fades or slices." That remains wrong.

[Cornbread]

I don't care for the way you've changed your tune, either. You originally said "hooks have more topspin than fades or slices." That remains wrong.

OK, now I'm puzzeled... should I blatently disagree with you I being hard to get along with. I post that I agree with most of what your saying and you reply that you don't care for my change of tune. Go Figure?

What I said early on in this discussion was, and I quote; "In general Hooks do have more topspin than Fades or Slices. But that is not a general statement that can be applied in every case ". If your going to summarize my statements, please include all my words. A more proper use of words by me may have have been ...' in general hooks are more likely to have topspin than fades '. Most folks realize that fades and slices are more prone to have been hit with an open face than Hooks, thus more loft, thus less likely to not have backspin. I'm guessing that if your married, you always have to get that last word in, should you argue. Everyone knows that a woman always has the last word. Anything after that is the beginning of a new arguement. :) Enought debating.. lets move on.

[iacas]

OK, now I'm puzzeled... should I blatently disagree with you I being hard to get along with. I post that I agree with most of what your saying and you reply that you don't care for my change of tune.

You're still arguing. If you were wrong and want to say you were wrong (you were), say "okay, I was wrong, I admit it." and be done.

What I said early on in this discussion was, and I quote; "In general Hooks do have more topspin than Fades or Slices. But

It can't be applied in ANY case. Hooks don't have more topspin than fades or slices. They all have zero topspin.

A more proper use of words by me may have have been ...' in general hooks are

That statement would also be wrong.

Most folks realize that fades and slices are more prone to have been hit with an open face than Hooks, thus more loft, thus less likely to not have backspin.

And yet the proper way to hit a draw is with an open clubface. A push-draw has more loft than a pull-fade. A push-fade would have the same loft as the push-draw.

And for the umpteenth time, no properly struck golf ball does "not have backspin."

Enought debating.. lets move on.

Please, by all means. I'm only responding to point out that you continue to be wrong. You stop posting, I stop responding. Easy.

[colin007]

just my insight, but perhaps people tend to think that draws have more roll/go farther because they (when done correctly) are hit from the inside. when a hack who usually hits a weak pull slice magically drops his hands inside and somehow hits an anomaly push draw and sees how far it goes (a 7 that usually goes 140 just went 160) he thinks that it had more topspin. not that he hit it better.

[shortstop20]

Why do people continue to suggest that a shot with less backspin somehow has more topspin?

Unless the ball is spinning clockwise, from a face on view after impact, the ball does not have topspin.

You cannot say a ball that's spinning(backspin) at 3000 RPM's has more topspin than a ball that has backspin of 4000 RPM, because neither of them have topspin. A reduction in backspin does not equate an increase in topspin.

[nevets88]

Someone get thee in front of a Trackman, top a ball and put this to rest. Trackman can see the type of spin, no?

[shortstop20]

Someone get thee in front of a Trackman, top a ball and put this to rest. Trackman can see the type of spin, no?

It's pretty unanimous that a topped ball has topspin.

.......but no well stuck draw/hook has topspin, none.

[zeg]

Why do people continue to suggest that a shot with less backspin somehow has more topspin?

Well, as an occasionally pedantic physicist, you CAN say that... in a purely mathematical sense, it does have 1000 RPM more topspin, it's just that its NET spin is still backspin. Of course, from a mathematical sense, backspin and topspin are both just spin on an axis parallel to the ground and perpendicular to the flight direction, one being a positive number and the other a negative.

But this sort of thing is why nobody likes physicists at parties...

[Zeph]

The ball will only spin in one direction, it cannot have sidespin and backspin. Let's say you have a golf ball that is struck perfectly square and has 0º sidespin, the ball would have backspin going straight through the center of the ball. If the clubface and swing path was not equal, you would get sidespin. Let's say the ball spins 10º either way. It will still have backspin, but rotated more to the side, which will give it "sidespin".

A 2000 rpm vs 3000 rpm shot has 1000 rpm less backspin, not more topspin. Topspin means the ball is rotating towards the target, which the ball almost never does, it just rotates at a slower rate towards the player.

The only way to put topspin on a ball with a square face, with an effective loft of 30º, would be to swing the club upwards 30º+ at impact, which means you would have to tee the ball up a foot or two. That is of course if you manage to keep the effective loft at 30º, it would open more and more the higher the club travels.

The other way to put topspin on a ball is by topping it, ie. hitting the top half of the ball with the leading edge of the club. You would not get any distance whatsoever, the ball would drop dead within 10-20 yards.

As long as the angle the clubface is moving at, is more downwards than the effective loft of the club, it is impossible to impart topspin to the ball with a proper stroke. A low-lofted driver, teed very high and with a swing bottom well behind, could in theory do it, but you still got the problem with the club gaining loft as it ascends. The less the difference in angles are, the less backspin you will impart, but never topspin. This is why the best players in the world impart more spin than high handicappers. Their swing bottom is 3-4 inches in front of the ball, so the club is travelling down at impact. Many high handicappers bottom out or even start up again at the time of impact, which will give poor distance and less backspin.

Example of a driver below, there is no doubt the ball starts spinning backwards. If the clubhead was travelling on an upward angle greater than the effective loft at impact, you would create topspin.

[shortstop20]

Well, as an occasionally pedantic physicist, you CAN say that... in a purely mathematical sense, it does have 1000 RPM more topspin, it's just that its NET spin is still backspin. Of course, from a mathematical sense, backspin and topspin are both just spin on an axis parallel to the ground and perpendicular to the flight direction, one being a positive number and the other a negative.

How can it have 1000 RPM or more topspin, or any topspin for that matter, when the ball is still backspinning?

You can't have both. The ball is either backspinning or topspinning.

[zeg]

How can it have 1000 RPM or more topspin, or any topspin for that matter, when the ball is still backspinning?

It's called superposition, and this is why you can also describe the top/backspin and sidespin separately. The ball is, of course, spinning on a single axis, but you can break that up into two components along orthogonal (perpendicular) axes, one pointing straight up from the ground, and one parallel to the ground and perpendicular to the flight direction. Given that choice of axes, you describe the spin of the ball fully using two number: the backspin and the sidespin. The backspin is a positive number if it's spinning back, and a negative number if it's spinning forward. Sidespin would be, say, positive for clockwise spin and negative for counter-clockwise (both these choices of sign could be reversed, it's entirely arbitrary).

So now say you've got a ball with no sidespin and 4000 RPM of backspin as your baseline. You write those two numbers as (sidespin, backspin), or in this case, (0, 4000). If you instead hit one with 3000 RPM of backspin, that'd be (0, 3000). These are vectors, and you can add or subtract them (more or less) like you would add or subtract regular numbers. So how different were the spins? Well, the rule for vector math is that the two numbers in the (a,b) pair are treated separately. So (0,3000)-(0,4000)=(0,-1000). That is the difference in spin. How would you say that? It's got -1000 "more" backspin, so that can equally well be described as having 1000 RPM "less" backspin or 1000 RPM "more" topspin (remember, negative backspin = topspin). This is ok because we are talking about relative amounts, not absolute amounts. Of course its total spin is still backspin, but remember how I said the choice of sign for whether positive or negative numbers represented back- or topspin was arbitrary? If we'd instead chosen to use positive numbers for topspin, we'd be going from -4000 RPM of topspin to -3000 RPM of topspin. That's the sense that we have "more" topspin---it's still a negative amount, but it's less negative. This is a bit counter to ordinary usage, but in terms of physics and math, it's correct usage. You can have "more" of something while it still being a less than zero amount. It's also confusing because backspin and topspin are not really different things, they're just labels for one thing (spin around the same axis) when it's positive or negative.

[jamo]

It's called superposition, and this is why you can also describe the top/backspin and sidespin separately....

Exactly. You can break down all of the different directions of spin that are imparted on the ball. It's like how an airplane can be moving upwards, but still have a downward acceleration due to gravity, even though it is outweighed by the upward acceleration caused by the thrust of the engines (and the airfoil and blah blah blah).

But this is all just semantics. No golf ball hit below the equator with a face with positive loft will have net topspin.

[zeg]

Exactly. You can break down all of the different directions of spin that are imparted on the ball. It's like how an airplane can be moving upwards, but still have a downward acceleration due to gravity, even though it is outweighed by the upward acceleration caused by the thrust of the engines (and the airfoil and blah blah blah).

Yep. Also, I feel compelled to correct myself---you need 3 numbers to completely specify the spin. Back/topspin, sidespin, and roll (axis along the flight direction). I didn't think about the last because it's probably usually quite small for a golf shot since it's not clear to me what, other than drag in the wind, would create a torque about that axis.

[sean_miller]

I'd think an off centre hit slightly opens or closes the clubface, leading to a slight push or a pull.

[shortstop20]

It's called superposition, and this is why you can also describe the top/backspin and sidespin separately. The ball is, of course, spinning on a single axis, but you can break that up into two components along orthogonal (perpendicular) axes, one pointing straight up from the ground, and one parallel to the ground and perpendicular to the flight direction. Given that choice of axes, you describe the spin of the ball fully using two number: the backspin and the sidespin. The backspin is a positive number if it's spinning back, and a negative number if it's spinning forward. Sidespin would be, say, positive for clockwise spin and negative for counter-clockwise (both these choices of sign could be reversed, it's entirely arbitrary).

I gotchya.

It seems that many believe a hook actually has topspin like a topped ball would though, with the absence of backspin.