Topspin Vs Bulletspin, Which is Faster?

[pobguy]

So, after introducing myself in the last post, let me post something more substantive here. If you look at the slides I posted, slide 5 shows the difference between final and initial height of ball. Keep in mind that these are real data from elite college pitchers. A positive value means the ball rose. That is, it was higher when crossing the plate than when released. Of course, the reason for that is primarily that it was thrown with a slightly upward initial trajectory. It was not the Magnus force (due to backspin) that made it rise.

 

[Ken B]

Welcome aboard! Hope you have time to spend and share. Looking forward to reading your posts and the link above.

Ken

 

[pobguy]

Some additional comments about some of the issues raised in this thread.

1. Someone upthread mentioned that a rise ball actually rises initially, then flattens out. Some great examples of that are in the slides I posted. See slides 11 and 12, which compare a rise (with backspin) to a drop (with topspin). The view is from the side.

2. All the softball data I have seen support the notion that the trajectories are smooth and the movement is continuous. That is even true of most (but not all) of the knuckleball trajectories I have analyzed. Keep in mind once again that I am talking about real data that use either video or radar tracking to give the position of the ball as it moves along its trajectory. Hard to argue with real data.

3. Regarding the original question posed in this thread: Assuming the ball is released at the same velocity and at the same location, I suspect there is very little difference in the time from release to home plate between topspin and bulletspin. Both pitches lose speed due to air resistance. There is some evidence from MLB data (sliders have a large amount of bulletspin) that the air drag is a tiny bit less on pitches with bulletspin than on other pitches, but the difference is too small to be of much practical significance. The point about there being more sideways or up-down movement on the topspin/sidespin pitch than on the bulletspin pitch is not relevant. The motion along the pitcher-catcher line is independent of any forces in the up-down or sideways direction, a fact that we teach early on in introductory physics classes.

 

[Greenmonsters]

Some additional comments about some of the issues raised in this thread.

1. Someone upthread mentioned that a rise ball actually rises initially, then flattens out. Some great examples of that are in the slides I posted. See slides 11 and 12, which compare a rise (with backspin) to a drop (with topspin). The view is from the side.

2. All the softball data I have seen support the notion that the trajectories are smooth and the movement is continuous. That is even true of most (but not all) of the knuckleball trajectories I have analyzed. Keep in mind once again that I am talking about real data that use either video or radar tracking to give the position of the ball as it moves along its trajectory. Hard to argue with real data.

3. Regarding the original question posed in this thread: Assuming the ball is released at the same velocity and at the same location, I suspect there is very little difference in the time from release to home plate between topspin and bulletspin. Both pitches lose speed due to air resistance. There is some evidence from MLB data (sliders have a large amount of bulletspin) that the air drag is a tiny bit less on with bulletspin than on other pitches, but the difference is too small to be of much practical significance. The point about there being more sideways or up-down movement on the topspin/sidespin pitch than on the bulletspin pitch is not relevant. The motion along the pitcher-catcher line is independent of any forces in the up-down or sideways direction, a fact that we teach early on in introductory physics classes.

Welcome Dr. Nathan! Please try to type slowly so we can understand. For example, I was right with you until you referenced slide 5. Is this the one titled "Drop"?

Now to the harder questions. re topic #1 above, where bolded, is it accurate to say that the ball rises above the release height but does not rise above its initial trajectory?

Topic #2 - If the vast majority of knuckleballs track smooth and continuously, of course they should be easy to hit (catch and/or capture), right?!!! You don't have to answer this.

Back to Topic #1 - Looking at slides 8-10, the pitchers' dropball (topspin) appear faster than their riseballs (backspin), which is consistent with most claims made here on DFP. In slide #7, if it is the the topspin pitch cluster (drop ball) that is circled in red in each graph that is called out, is it possible to ID the spin axis and type of pitch that are the fastest i.e., low spin and 70+mph?

Slide #7 - spin rate v. speed graph - there are several pitches at 3000+ rpms. This equates to 50+ rps. Reported Rev fire recorded pitches rarely exceed 30 rps (even with the bucket parent multiplication factor). Any thoughts on this re accuracy etc?

And lastly, if I understand correctly that increasing or decreasing the spin rate on a pitch thrown at the same initial velocity affects the final velocity, what pitch (rpms, spin axis, pitch type) can be thrown the fastest?

Feel free to answer in the context of baseball if you're more comfortable with that dataset.

I'll thank you in advance for you time just in case you disappear from the forum after this post. Not that I'd blame you one bit!

PS If you do decide to stick around, I can't promise anything, but we might be able to start a sticky thread titled - "Go Ask a Physicist"

 

[pobguy]

1. I was right with you until you referenced slide 5. Is this the one titled "Drop"?

2; Now to the harder questions. re topic #1 above, where bolded, is it accurate to say that the ball rises above the release height but does not rise above its initial trajectory?


3. If the vast majority of knuckleballs track smooth and continuously, of course they should be easy to hit (catch and/or capture), right?!!! You don't have to answer this.

4. (a) Looking at slides 8-10, the pitchers' dropball (topspin) appear faster than their riseballs (backspin), which is consistent with most claims made here on DFP.
(b) In slide #7, if it is the the topspin pitch cluster (drop ball) that is circled in red in each graph that is called out, is it possible to ID the spin axis and type of pitch that are the fastest i.e., low spin and 70+mph?

5. Slide #7 - spin rate v. speed graph - there are several pitches at 3000+ rpms. This equates to 50+ rps. Reported Rev fire recorded pitches rarely exceed 30 rps (even with the bucket parent multiplication factor). Any thoughts on this re accuracy etc?

6. And lastly, if I understand correctly that increasing or decreasing the spin rate on a pitch thrown at the same initial velocity affects the final velocity, what pitch (rpms, spin axis, pitch type) can be thrown the fastest?

1. Yes..."drop" in this case is just the difference between final and initial height of ball. So, for all 3k or so pitches, we measure the "drop", the put that pitch in the appropriate "bucket", and then plot the number of pitches in each bucket. That is what the plot shows. All pitches with a positive drop (by my definition) end up higher than they started.

2. Yes. More precisely, if you draw a line tangent to the initial trajectory, the actual trajectory lies below that for all pitches. That is another way of saying that the upward Magnus force due to the backspin is less than the downward force of gravity.

3. The trajectory is smooth but the direction of the movement is random from one pitch to another. No one knows which way it will break, which makes it hard to hit and equally hard to catch.

4. (a) True for Thomas; not so true for Henderson.
(b) Yes. I had a student analyzing these data last summer and she did all those pitch identifications. But I don't know the answer off the top of my head. The plots on Slide 7 are very very informative, allowing a snapshot view of what kinds of pitches each pitcher throws, speed, movement.

5. For these data, I really don't have an answer. The cameras were a "traveling unit" used for the ESPN broadcast, unlike the permanently mounted cameras used in MLB. However, I also don't know about the accuracy of RevFire.

6. The spin rate does not seem to have much of an effect on the final velocity, assuming the same initial velocity. At least that is my experience from having analyzed 1000's of MLB pitches.

 

[Rocketech1]

So Dr Nathan if you would have to guess, how fast and many RPS would a human have to throw a softball to make it rise above its initial plane of trajectory?

 

[JJsqueeze]

Hello...I am new to this forum, although my name (Alan Nathan) has been raised various times in this particular thread. Thanks to Rick Pauly for posting a link to my article about late break and to others for links to my knuckleball research. Although my research is primarily in the physics of baseball, I have done a bit of work analyzing PITCHf/x data for softball. I actually have all the PITCHf/x data from the 2011 WCWS and gave a talk about the data back then. Here is a link to the slides: http://baseball.physics.illinois.edu/ppt/NathanWCWS.ppt. Rather than beat up on each other about various things I have written that you may agree or disagree with, you can now beat up on me directly. Since I consider myself an educator, I'll do my best to explain my points of view. As a scientist, I have an open mind and very much like to hear from those who have other points of view. Time permitting, of course.

Welcome aboard. You have no idea how valuable a physicist with your interests is to our motley crew.

 

[JJsqueeze]

2. All the softball data I have seen support the notion that the trajectories are smooth and the movement is continuous. That is even true of most (but not all) of the knuckleball trajectories I have analyzed. Keep in mind once again that I am talking about real data that use either video or radar tracking to give the position of the ball as it moves along its trajectory. Hard to argue with real data.
QUOTE]

One big thing that I could not discern from your website was what you mean by smooth as it relates to curvature. For instance, both the curvature of a circle and a parabola are "smooth" but one is constant and the other changes with position. As we have discussed late break here, I think there are basically two positions, the first is that the curvature is a constant arc as it would be on a circle and the other is that the curvature changes as it would be on a parabola. I think the circular people are the "no late break" folks. The parabolic folks (late breakers-including your truly) think that while it is still "smooth" that the majority of the break on a good breaking pitch is further along in the travel. Set us straight.

the other thing I am really curious about is whether, based on your research, can a knuckleball break in more than one direction in a single pitch (hint-say yes so I don't have to eat humble pie).

 

[pobguy]

So Dr Nathan if you would have to guess, how fast and many RPS would a human have to throw a softball to make it rise above its initial plane of trajectory?

I'll have to get back to you on that.

 

[Rick Pauly]

Alan
Absolutely great to have you posting on this site. We have some excellent posters and lots of people starving for information. Once in a while we get a little rough around the edges, but in general the info on this site has helped a ton of young aspiring pitchers. Again, welcome.
Rick Pauly

For interested readers, I had the pleasure of spending the better part of a day with Alan last spring while attending one of his lectures. For someone like me who thinks he knows a lot about the physics of pitching/hitting, it is very humbling to have discussions with Alan....and as you will see, if he isn't educated on a certain subject he will tell you. He doesn't have a dog in the fight so he lets physics laws and test data do his talking.
We will truly be blessed if he continues to frequent this site.

Hello...I am new to this forum, although my name (Alan Nathan) has been raised various times in this particular thread. Thanks to Rick Pauly for posting a link to my article about late break and to others for links to my knuckleball research. Although my research is primarily in the physics of baseball, I have done a bit of work analyzing PITCHf/x data for softball. I actually have all the PITCHf/x data from the 2011 WCWS and gave a talk about the data back then. Here is a link to the slides: http://baseball.physics.illinois.edu/ppt/NathanWCWS.ppt. Rather than beat up on each other about various things I have written that you may agree or disagree with, you can now beat up on me directly. Since I consider myself an educator, I'll do my best to explain my points of view. As a scientist, I have an open mind and very much like to hear from those who have other points of view. Time permitting, of course.