How-To "Backspin on chips"

BrianW · #31 (**permalink**) 03-24-2008, 11:53 PM

Mox,

Please don't take my word for it, carry out some investigation and see what all scientific research reveals on the subject. I know that golfers feel like they are pinching the ball into the turf and that may well be a good swing thought that helps them, it does not detract from what actually happens though.

I am relating to you what I have deducted from scientific research using high speed photography and research into the ballistics of ball contact. It really does not mater to me if you wish to disbelieve it and I am not attempting to ridicule your theorising. I have had a number of these discussions but have not found them able to give a substantive argument.

Enjoy the game my friend.

bill reed · #32 (**permalink**) 03-24-2008, 11:56 PM

hi Mox
how can you hit down on the ball when even with the ball on a tee and with a driver its the bottom half of the ball that compresses.
with an iron you cannot hit the ball downward as the face of the club has so much loft, the only way you can hit down is if you lean the shaft below your knees and even then you only come into the middle of the ball and not above the center. to hit down you have to apply downward pressure and it cant be done with a a golf club with the loft we use. try picking any club out your bag and try and do it you will see it imposable to do and it the loft of the face that stops you doing it. you cant push a ball downward using something wedged shaped like a golf club.
swinging down with a steep swing get you more backspin as the ball runs up the club face more. why do you get the same backspin when playing of fairways with short and long grass and playing it in the first cut of rough, playing out the rough you get less backspin only because grass gets between the face and the ball. if you nip the ball out the sand in a fairway bunker you can still get backspin and only take sand after the ball.
if you were to put a club against a ball in your hand you would see you cant hit down on a ball only swing down.
cheers
bill

Mox · #33 (**permalink**) 03-25-2008, 01:53 PM

Like I said - further debate would likely be pointless, but still ...

Bill, Yes - you CAN (and DO) apply forces in a direction into the ground. The wedge shape of the club does not change that. The MOTION of the wedge shape is relevant, and being downward as well as forward, it applies forces in both directions. Putting a static club head next to a ball is completely irrelevant. The club head MOVES at the time of impact, and during the time the ball is compressed. It moves forwards and DOWNWARDS.

Get a soccer ball. Put it on the ground. Place one finger on top of the ball (not necessary if you have 5000fps eyesight). Put your other hand - in a wedge shape - behind the ball, below the equator. Press directly forward. Will the ball slide? Yes - quite easily.
Now do the same, but instead of pushing directly forward with the "wedge hand", now press forward as well as downward. Will the ball slide? Yes it will. Just as easily? Not it won't! Why? Because the downward forces you apply to the ball is causing increased friction between the ball and the ground.

Try it with a balloon, you will easily see it compress into the ground.

The forces are there, and they are more than marginal.

Read bullet #3 here

Quote:

3. At address place the ball in a position where it is slightly behind where the club will make contact with the ground – keep your hands slightly ahead of the club. This allows the club to connect with the ball on the downswing creating a divot after you have struck the ball. This forces the ball either into the ground or to “climb” back along the club face over the grooves. As the ball cannot go into the ground it is forced to climb over the club face where the grooves grip the ball and create the backspin. One of the reasons it is so difficult to get spin out of a fluffy lie is because hitting down on the ball allows the ball to go forward into the grass (rather than back over the grooves), and the grass getting between the grooves and the ball limits or negates backspin.

Greg Norman has some feelings about this.

Quote:

It's also important to hit slightly down on the ball. One of the reasons I'm able to apply so much spin is that I have a fairly upright swing which enables me to hit down rather steeply on the ball. When I want to, I'm able to make impact with the top-back quadrant of the ball. I actually squeeze the ball down against the turf, applying enormous friction and backspin. I don't take much of a divot; it's more like a crease in the turf or a slackening down of the grass.

Short Game guru Dave Pelz:

Quote:

Use a sand or lob wedge, move your hands and weight slightly toward the target, and play the ball well back in your stance so you're sure to trap it between the clubface and the ground.

That last article is actually a very good answer to the original question in this topic.

Oh - and for golfingguy - I don't think anybody is talking about distance. It's purely about spin-rate.

I choose to believe the combined knowledge of Tiger, Greg Norman, Dave Pelz and my high school physics teacher.

BrianW · #34 (**permalink**) 03-25-2008, 02:47 PM

Quote:

Originally Posted by Mox

Like I said - further debate would likely be pointless, but still ...

Bill, Yes - you CAN (and DO) apply forces in a direction into the ground. The wedge shape of the club does not change that. The MOTION of the wedge shape is relevant, and being downward as well as forward, it applies forces in both directions. Putting a static club head next to a ball is completely irrelevant. The club head MOVES at the time of impact, and during the time the ball is compressed. It moves forwards and DOWNWARDS.

Get a soccer ball. Put it on the ground. Place one finger on top of the ball (not necessary if you have 5000fps eyesight). Put your other hand - in a wedge shape - behind the ball, below the equator. Press directly forward. Will the ball slide? Yes - quite easily.
Now do the same, but instead of pushing directly forward with the "wedge hand", now press forward as well as downward. Will the ball slide? Yes it will. Just as easily? Not it won't! Why? Because the downward forces you apply to the ball is causing increased friction between the ball and the ground.

Try it with a balloon, you will easily see it compress into the ground.

The forces are there, and they are more than marginal.

Read bullet #3 here

Greg Norman has some feelings about this.

Short Game guru Dave Pelz:

That last article is actually a very good answer to the original question in this topic.

Oh - and for golfingguy - I don't think anybody is talking about distance. It's purely about spin-rate.

I choose to believe the combined knowledge of Tiger, Greg Norman, Dave Pelz and my high school physics teacher.

Mox,

You are creating questionable statements to support an incorrect theory. Come on now, do you really believe the ball gets compressed between the tee and clubface in a way that can contribute to velocity and spin? The ball meets the face at force of around 2500 pounds

I agree that many eminent golfers claim that the ball gets trapped with the turf and that is how spin is generated but they are wrong, these people are not speaking from scientific experimentation they are talking of what it feels like, I am not convinced your school physics teacher ever studied club/ball ballistics either.

The tremendous forces created when the lofted clubface meets the ball pushes it backwards and upwards not downwards, how can soft earth and grass compress a golf ball that is struck with these forces. Take a golf ball and see if you can compress it in your hands, try it in a vice, it is very hard and does not compress easily, dirt has no chance.

Here is an excerpt again from Mt Tutelman's site that explains and he knows a bit about golf:

Impact lasts no more than a half millisecond.
The clubhead moves less than an inch during this time.
The force between clubhead and ball can peak between 2000 and 3000 pounds. (It can average about 1900 pounds over the 0.4 millisec of impact. The peak is between 1.4 and 2 times the average force.)

So what is actually going on during that half-millisecond or so of impact? Here's the story, as described by Cochran & Stobbs -- and in somewhat more detail by Gobush:

In the first microsecond of impact, we have the irresistable force meeting the immovable object. The ball has to react somehow to the momentum of the clubhead, and the least-energy way it can react is by moving up the lofted clubface. Initially it slides up the clubface, because there isn't enough friction yet between clubface and ball. But all that is about to change very quickly.
The ball cannot acclerate to an upwards velocity in no time at all; that would require infinite acceleration, which requires infinite force. So it can't get completely out of the way of the clubhead just by sliding upwards. It begins to compress on the clubface, which creates a force between the clubface and the ball. If you don't think this is a large force, just try to compress a golf ball by 30% of its diameter using your fingers. Not even close! OK, use a vise; it's still very hard to apply that much compression force. Remember, this is a force that averages almost 2000 pounds during impact, and can easily peak around 3000 pounds. This force of compression does two important things:
- It begins to accelerate the ball with a horizontal component, not just the vertical motion up the clubface.
- It creates a lot of friction between ball and clubface. So, instead of sliding up the clubface, the ball begins to roll instead.
The ball continues accelerating upwards (due to the loft) and horizontally (due to the compressive force). The sliding has turned completely into roll, so the upwards acceleration increases the speed of roll. At some point, the momentum absorbed from the clubhead through acceleration has the ball moving faster than the clubhead. In other words, the elastic rebound of the ball's acceleration allows the ball to release from the clubhead. At this instant, its launch conditions are determined.

Mox · #35 (**permalink**) 03-26-2008, 12:13 AM

Ok, so you are now telling me, that the ball moves up, based on forces pushing down and forward?

Imagine that the ball was under no influence from gravity and hanging freely in midair, with no contact with the ground.

Now hit it with forces moving down and forward. Will the ball move up?

That ball begins sliding upwards, because it reacts to the downward force applied.
Action equals reaction, remember.

Explain why spinrates are different from fairway to sand and to hardpan, if friction is not involved. Have you ever tried to hit a spinning shot off a concrete path? It'll spin like crazy!

Never mind. This is pointless. Forget about it. We just disagree. I'm not going to bother anymore.

bill reed · #36 (**permalink**) 03-26-2008, 09:52 AM

hi Mox
the ball moves up because of the loft of the club face. how much it moves up depends on how much loft id applied. that why when using a putter the ball hardly lifts of the ground at all and why with a one iron the ball comes off the face of the club lower than if you used a wedge. the angle of loft makes the ball compress into the face and the angle of the face determines the angle the ball leaves the club face.
again it is not a downward hit on the ball as the face of the club hits below the center of the ball and that gives the ball and upward blow not a downward blow.
if you hit the ball with a club with no loft then the ball would travel in a slightly downward motion. but you don't you use a club with loft then the ball leaves the face on the same angle as the face. if you have a 10.5% driver then the ball comes of the face about 12%, if you use a 52% wedge the ball comes of the face about 52/54%.
if what you say was true then people in hat sunny places would be playing on hard fairways and people like me on most wet fairways and our clubs would have to be tweaked for the diffrent conditions as we cant trap the ball the same as the ground is harder there and softer here. that just does not happen.
cheers
bill

BrianW · #37 (**permalink**) 03-26-2008, 10:21 AM

Quote:

Originally Posted by Mox

Ok, so you are now telling me, that the ball moves up, based on forces pushing down and forward?

Imagine that the ball was under no influence from gravity and hanging freely in midair, with no contact with the ground.

Now hit it with forces moving down and forward. Will the ball move up?

That ball begins sliding upwards, because it reacts to the downward force applied.
Action equals reaction, remember.

Explain why spinrates are different from fairway to sand and to hardpan, if friction is not involved. Have you ever tried to hit a spinning shot off a concrete path? It'll spin like crazy!

Never mind. This is pointless. Forget about it. We just disagree. I'm not going to bother anymore.

Regarding hardpan and a fluffy lie:

Have you ever noticed how a ball that's "sitting up" will fly higher when struck than a ball that is resting upon hard pan? The launch angle is greater in the first case because the ball's centroid is situated higher than the clubhead's centroid at impact.

In this illustration, (Dam, it has been deleted somehow) we show two situations. At the left, we show a golf ball sitting pretty close to the ground at impact. On the right, we show a ball that's "sitting up", perhaps upon a tuft of grass. Those arrows do not represent the respective launch angles. They simply illustrate the relative positions of the centroids at impact. (Aside: The higher the arrow points, the more the clubhead's face angle will increase at impact due to temporary bending, further complicating calculations!)

When momentum is transferred from the club to the ball on the left, the launch angle will be shallow because the ball's centroid is not much higher than the clubhead's.

But a ball that sits up has an elevated centroid which a golfer can easily "get under". In this case, the club's centroid is so low with respect to the ball's that this launch angle is likely to be quite vertical and a flop shot will result.

That's OK Mox, I am not looking for a bust up only debating what happens to golf balls at impact

Lets leave it at that then my friend.

Neil18 · #38 (**permalink**) 03-26-2008, 11:25 AM

Great debate guys,

I'm in Brian and Bills school here.

If Norman reckons he contacts the ball on the upper rear quadrant of the ball for extra spin, he is a little dillusional! If we'd hit a ball there you just bury it in the ground.

It is physically impossible to hit the ball any higher than the equator if we are to get it air born. Even though the clubhead mass is moving in a slightly descending direction, the loft on the face (and ball position depending on 2 iron or wedge) is at an angle greater than the angle of descent. Always. Hence the ball cannot move down. Even for 0.0000000000001 seconds.

Even if we hit it flat, square on the equator of the ball (the highest point possible) we would need a club with negative loft to place any force into the ground through the ball.

So, clubhead mass goes slightly downwards, loft of club is always greater than angle of descent, combination of the two = piercing shot with plenty of spin.

Mox · #39 (**permalink**) 03-28-2008, 09:09 AM

[QUOTE=Neil18;10551983]
It is physically impossible to hit the ball any higher than the equator if we are to get it air born. Even though the clubhead mass is moving in a slightly descending direction, the loft on the face (and ball position depending on 2 iron or wedge) is at an angle greater than the angle of descent. Always. Hence the ball cannot move down. Even for 0.0000000000001 seconds.
[quote]

Have you ever seen a billards player hit a massé shot?

It is absolutely possible to hit a ball higher than the equator, and it WILL compress the the ball into the ground and kick it into the air with massive backspin.

It's a matter of DIRECTION how forces is applied to the ball. The loft only has influence as the ball react to the forces applied!

You Tube

Neil18 · #40 (**permalink**) 03-28-2008, 09:15 AM

Mox Mox Mox!

Now I understand where our differences are!

You're playing golf with a cue!

I should have said "you can't hit the ball above the equator with a golf club"!

As we are using clubs, not cues, your example (although a valiant attempt) is not applicable.

The only way to hit a golf ball with a golf club above the equator is to thin it, or ram it straight into the ground with negative loft.

BrianW · #41 (**permalink**) 03-28-2008, 09:23 AM

[quote=Mox;10552040][quote=Neil18;10551983]
It is physically impossible to hit the ball any higher than the equator if we are to get it air born. Even though the clubhead mass is moving in a slightly descending direction, the loft on the face (and ball position depending on 2 iron or wedge) is at an angle greater than the angle of descent. Always. Hence the ball cannot move down. Even for 0.0000000000001 seconds.

Quote:

Have you ever seen a billards player hit a massé shot?

It is absolutely possible to hit a ball higher than the equator, and it WILL compress the the ball into the ground and kick it into the air with massive backspin.

It's a matter of DIRECTION how forces is applied to the ball. The loft only has influence as the ball react to the forces applied!

http://www.youtube.com/watch?v=C8zXzUVnEtQ

Mox,

Of course you can do that with a Billiard cue but that is a completely different device and action than using a golf club, it is not comparing apples with apples. Try that shot if the end of the cue was 6 CM wide, sloping back at 45 degrees, striking the ball at a force of one ton with grass under it

Oh! and it is not possible to hit the ball out of the sweet spot higher than the equator, you can only do that with the leading edge and the ball will squirt out flat.

Mox · #42 (**permalink**) 03-28-2008, 09:29 AM

Quote:

Originally Posted by Neil18

The only way to hit a golf ball with a golf club above the equator is to thin it, or ram it straight into the ground with negative loft.

You still think it is about the angle of the clubface. It is not. It is about the DIRECTION of the clubface at impact. That is what applies force to the ball.

What my example proves, is that a downward force applied to a ball DOES trap the ball against surface and club face (or cue tip). It DOES compress the ball against the surface. Forces DO react back from the ball to the club face (or cue tip), causing prolongued contact at higher compression, resulting in MORE spin.
Whether the contact surface is a lofted wedge or a rounded cue tip makes NO DIFFERENCE to the principles of physics involved.

And I'm sure you'll find, that billards players are even able to hit the ball below the equator, on a DOWNWARD trajectory, to create massive backspin.

It's the same principle that applies. You hit DOWN on the ball, compress it between cue tip/club face and surface/ground. The resulting opposite forces prolongues and enhances the contact with the cue tip/club face, creating the enhanced spin.

Mox · #43 (**permalink**) 03-28-2008, 09:33 AM

Quote:

Originally Posted by BrianW

Of course you can do that with a Billiard cue but that is a completely different device and action than using a golf club, it is not comparing apples with apples. Try that shot if the end of the cue was 6 CM wide, sloping back at 45 degrees, striking the ball at a force of one ton with grass under it

What? You think the principles of physics changes?

The same principles apply! It is not about clubface loft. It is about DIRECTION OF FORCE!

BrianW · #44 (**permalink**) 03-28-2008, 10:13 AM

Mox,

Take a look at these video sequences. Please do not say the ball is pinched between the clubface and rubber tee to compress it

You should be able to see that the ball is only in compression on the clubface with the driver and iron.

You Tube

Mox · #45 (**permalink**) 03-28-2008, 10:22 AM

I don't know what your purpose is with showing this video again.

As already established, the driver DOES compress the ball (slightly) against the tee. On top of that, Driver shots are meant to be UPWARD strikes to REDUCE spinning. The purpose of THIS topic is to MAXIMIZE spinning, so talking about swing trajectories that does the opposite is irrelevant.

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