Ball Actually "Pinched" Against Ground or Not

[Augusta Hacker]

Hey iacas....get your head out of your dairy-aire.....first, I am talking about the exact moment in which the ball is struck. Although it is a milli-second, it can be analyzed for impulse and momentum. I am fully aware of how the loft of the club affects the ball the milli-second after the strike but for this discussion, we are talking about the "pinching" sensation and whether it exists. It has been my stance all along that at this small moment in time, there is a downward and forward force imparted in the ball creating the pinch. I am also aware of the affects of static and kinetic friction imparted on the ball by the club face as well as the friction created by air resistance. The diagram is not to scale, of course not, if it was you would not be able to differentiate. However, you admit that the pros have 4-8 degrees of downward blow....by using simple trigonometry, you can determine the downward vector using the amount of force applied at the 4-8 degree downward blow.

If you want to argue with the laws of science, I suggest you reread Newton's Laws of Motion, the basis of which dynamics and kinetics are founded. I do agree with you that the amount of downward force is minimal but it is in fact there. Question for you, if there is a minimal amount of force downward, where does it go after impact? Does it just vanish? No, it is reacted to by the ground thus the pinch.

To your question to hitting the ball out of rough, again, you make my arguement. The downward blow creates backspin.....correct? In rough, it is much more difficult to create backspin since there is not anything other than the club face to create that spin. Without the pinch and compression created by the ground, you cannot create the spin out of the rough if you truly do not meet any resistance and "scoop" the ball.

[niblick]

Here's a slow of impact by a guy who hits down on it as much as anyone.



Check out the close up of impact. Augusta Hacker can grandstand all he wants and it just gets funnier.

The. Ball. Never. Moves. Down.

[Augusta Hacker]

Here's a slow of impact by a guy who hits down on it as much as anyone.

It never moves down because of the ground.....I always thought science was funny myself. If the ground does not impose backspin on the ball, how come it is difficult to spin the ball out of the rough? When the ball does not have a solid surface underneath to squeeze against?

[Finnstang]

It never moves down because of the ground.....I always thought science was funny myself. If the ground does not impose backspin on the ball, how come it is difficult to spin the ball out of the rough? When the ball does not have a solid surface underneath to squeeze against?

Too much grass between the club face and the ball to get solid contact with the grooves.

[Augusta Hacker]

These guys also agree the ball is compressed into the ground..

Here is a PGA intructor......
http://www.golftipsmag.com/instructi...o-contact.html
"It’s a solid strike that compresses the ball against the ground and takes a divot after the ball is in the air, not before. "

And this guy is pretty good too.....I think he knows a little something about a golf swing.... http://www.golfdigest.com/instructio...gertips_gd0703
"It also helps if you turn the knuckles of your top hand to the ground through impact, like I'm doing here. This is a clear sign that you're compressing the ball, trapping it between the clubface and the turf, which will result in a divot on the forward side of the ball."

[BigAl5150]

These guys also agree the ball is compressed into the ground..

Really? Neither say the ball is compressed INTO the ground (neither do the one's below either). They say AGAINST the ground. That is a pretty big difference. Again, that's also the

feeling they have, not the reality. Watch the videos provided in the thread. "To hit irons solidly, which is the key to distance control, you need to hit down and compress the ball between the ground and the face of the club." "This is a clear sign that you're compressing the ball, trapping it between the clubface and the turf, which will result in a divot on the forward side of the ball." "This type of "trapping" sensation allows for the ball to compress against the ground. As a result, the ball penetrates the air and achieves maximum distance."

[Augusta Hacker]

Really? Neither say the ball is compressed INTO the ground (neither do the one's below either). They say AGAINST the ground. That is a pretty big difference. Again, that's also the

My bad....I mis-typed.....however, they do say to compress the ball between the ground and club and that is exactly what I have been saying. Who are we to argue with Tiger Woods?

ETA: They do not say "feel like you compressing the ball" but say "to compress the ball". That is a big difference.

[BigAl5150]

"The face of the club will then contact the surface of the golf ball just prior to reaching the bottom of the swing arc. As a result, the ball becomes trapped between the descending clubface and the ground. The ball compresses. Because the face of the clubhead is lofted, the ball - rather than be driven into the ground as a downward hit might imply - will spin backwards up the clubface, decompress (adding energy to its escape) and climb into the air. The angle at which the ball climbs (trajectory) will be directly related to the loft of the club we have chosen for the shot."

Read the rest here.

[Augusta Hacker]

"The face of the club will then contact the surface of the golf ball just prior to reaching the bottom of the swing arc. As a result, the ball becomes trapped between the descending clubface and the ground. The ball compresses. Because the face of the clubhead is lofted, the ball - rather than be driven into the ground as a downward hit might imply - will spin backwards up the clubface, decompress (adding energy to its escape) and climb into the air. The angle at which the ball climbs (trajectory) will be directly related to the loft of the club we have chosen for the shot."

The ball compresses and goes up the face....I have been saying that all along. The only difference is that I am saying for a milli-second, it is compressed against the ground and then up the club face. That is all.

[iacas]

The only difference is that I am saying for a milli-second, it is compressed against the ground and then up the club face.

Nope.

If the ground does not impose backspin on the ball, how come it is difficult to spin the ball out of the rough? When the ball does not have a solid surface underneath to squeeze against?

Wow, seriously? You still think the ground has anything at all to do with backspin? Seriously?

It's difficult to spin the ball out of the rough because the grooves can't effectively channel away debris, and the ball slides up the clubface more than it rolls up the clubface. C'mon.

Hey iacas....get your head out of your dairy-aire.....

I've warned you about this sort of tactic already today, and I'm not standing for it anymore. At this point I'm inclined to believe you wrote "dairy-aire" because you simply don't know how to spell derriere.

first, I am talking about the exact moment in which the ball is struck. Although it is a milli-second, it can be analyzed for impulse and momentum.

Not in the way you've done.

You're pretending that friction is some massive force, when in reality it's only a fraction of an already small downward vector. At the same INSTANT that your frictional forces begin to work, the ball begins moving UP the clubface because the much, much, much larger FORWARD force vector, translated into both forward and upward force vectors by the club's LOFT. The ball never moves down, regardless of how small an amount of time you want to ascribe to it. And if the ball moves down for a millisecond (or less, and it does not), what's the freakin' point in debating it? It's pointless.

I am fully aware of how the loft of the club affects the ball the milli-second after the strike but for this discussion, we are talking about the "pinching" sensation and whether it exists.

The "pinching sensation" does exist. Nobody's debating that. I've admitted to using the term itself.

However, that's NOT what's being debated. What's being debated is whether or not the ball goes down or not. It does not. For the ball to go down and then start coming back up, it would have to somehow "bounce" off the ground. That doesn't happen - witness the several tee shots we've seen of a ball being hit from a tee. Tee a ball up in the air and hit it with an iron - you still get backspin. If it didn't "bounce" off the ground (you can still spin the ball even when it's not sitting on the ground), the forces would have to change to cause the ball to move a different direction. That ALSO does not happen.

It has been my stance all along that at this small moment in time, there is a downward and forward force imparted in the ball creating the pinch.

You're not listening to me: that forward force (which is much, much bigger than the frictional co-efficient applied by a relatively small downward vector) is translated into a substantially large UPWARDS vector that, at the instant of impact, drastically overmatches the teeny downward force you keep wanting to talk about.

If you want to argue with the laws of science, I suggest you reread Newton's Laws of Motion, the basis of which dynamics and kinetics are founded.

I probably took a lot more physics classes than you: I don't need to re-read Newton's Laws of Motion in order to debate someone who seemingly forgot some of what he learned in Physics 101.

I do agree with you that the amount of downward force is minimal but it is in fact there.

Yet you continue to ignore the massive upwards force created along the normal axis that connects center of ball to clubface.

Question for you, if there is a minimal amount of force downward, where does it go after impact?

It doesn't "go" anywhere - you're the one that's ignoring a force: the forward vector translated into a normal force perpendicular to the clubface. That creates a (relatively) huge upwards force.

Is the result of this math equation positive or negative:

None

[Augusta Hacker]

Tell you what iacas....you can argue the point with several PGA instructors.....and Mr. Tiger Woods himself. I am done with you.

[iacas]

Another thing: friction opposes the direction of movement. If you drag a block across a surface to the left, friction points to the right.

There's no true "surface" in a golf ball because the club and the ball are both moving, but for the purpose of a free body type diagram with force vectors, the clubface can be thought of as the surface.

Which way does the frictional force point? Downward. Thus, which way is the ball sliding? Upward (relative to the clubface).

Let's take a strong 3-iron at 19 degrees. Let's hit down on it six degrees and have the shaft leaning forward six degrees (both of which are a bit extreme for a 3-iron, but I'm giving you the benefit of the doubt). At impact, the club will still have 13 degrees of positive loft.

So in effect, we have a clubhead with 13 degrees of loft striking the ball on a path that's six degrees downward. The clubhead will be moving at, say, 100 MPH. That's 10.5 MPH of force "downward" and 99.5 MPH of force "forward." Since the clubface is still leaning back from the ball 13 degrees, do you honestly believe that 10.5 is going to counteract 99.5 on an inclined plane of what amounts to negative 13 degrees (away from the ground), particularly when you're relying on FRICTION (μ < 1) to do so?

The math gets worse from there as you hit more realistic shots (not six/six with a strongly lofted three-iron) with higher lofted clubs.

[iacas]

Tell you what iacas....you can argue the point with several PGA instructors.....and Mr. Tiger Woods himself. I am done with you.

Tiger Woods himself probably knows the ball doesn't actually bounce off the freakin' ground, and I can certainly tell you he knows how to generate spin and why the rough affects spin.

As I and many others have said, what you FEEL or what you TELL a student to feel is not necessarily what occurs in reality.

[Augusta Hacker]

Tiger Woods himself probably knows the ball doesn't actually bounce off the freakin' ground, and I can certainly tell you he knows how to generate spin and why the rough affects spin.

Well, I stand corrected....after years of reading and believing....I had to see it to believe it. This video ends the debate and I am wrong....While I still maintain there is a downward component of the swing, it is insignificant and too small to prevent the ball from overcoming the force of static friction of the grooves on the club face.

There are actually several SwingVision videos of other PGA professionals on YouTube for your review as well. Hard headed I am , but can admit when I am wrong and the videos prove it. One good thing out of this debate is that it should translate to better ball striking on my part in the future......so I have that going for me.

[iacas]

While I still maintain there is a downward component of the swing

There is, but that was never being debated. Of course you hit down and let loft get the ball up.

it is insignificant and too small to prevent the ball from overcoming the force of static friction of the grooves on the club face.

I'll ignore that the grooves really have little to do with this topic at this point, and simply accept your acknowledgment of your errors.

Others have posted videos before. I guess you missed those. Look at the Boo Weekley one, too - he's hitting a shorter iron and thus de-lofting even more.

[Augusta Hacker]

Is the Boo Weekley video linked in this thread?

[Arathel-bwcc]

Both of you use big worgs that I don't understand! Glad this is resolved.

[powerfade]

Whew...we finally have closure?

Leadbetter advocates a trap (pinch) for mid and short irons. I always took that to mean 'hit down' as opposed to 'sweeping' those irons.

You guys took pinching to a whole new level!