Is it a rise?

[pobguy]

This plot is the same pitch as the previous except that the spin in increased to 2000 rpm (backspin). Note that the ball approaches home plate nearly horizontally (but still on a slightly downward path). And again note that the trajectory never rises above the red line.

 

[Easton33]

This is the point that all those questioning your data arent understanding: that the direction of force at release (vector) of ALL underhand fastpitches is slightly upward leading to an initial upward trajectory of the ball, not parallel to the groud plane as all seem to think.

Actually, my point is math is not subjective. Nasa scientists, college physicist, and I am not sure what the discipline of the other 2 college professors are that provided the info for the link, (credit is at bottom of scale) but their numbers are not close to each other. My question is why? Sluggers quoted numbers from the rocket scientist calculator, is a foot off over a 40' when compared to pobguy. 4.5' vs 3.5' respectively. That is a big difference over 40'. Will the answer to this question affect me or dd? Not in the slightest but we may find a new gravitational force against the yellow ball that may lead to a revolutionary break through in time/space travel.

 

[pobguy]

their numbers are not close to each other. My question is why?

The NASA calculations and my own are not so different. There might be small differences due to different assumptions about the air drag, since there can be variations in drag due to temperature, elevation, surface roughness of ball, etc. I guarantee that if air drag were eliminated, we would all get exactly the same trajectory for the gravity-only case. That is a calculation that is done by week 2 of an introductory physics course.

However, one should not focus on the differences in these different calculations but rather their similarities. The point of these calculations is *not* to predict with precision the trajectory of the ball but rather to demonstrate the qualitative effects that occur due to backspin, topspin, etc. For example, these calculations clearly show that a rise ball really can rise, meaning it crosses the plate above the release point. Also they show that for any reasonable amount of spin, the trajectory never rises above the projection of the initial direction (the red line in my graphs). The calculations show that the height of the ball as it crosses the plate is very sensitive to the release angle of the pitch, regardless of the spin axis. The calculations also show that the ball drops more with topspin than with gravity alone. These are all useful things to know and understand, at least at the qualitative level.

 

[Doug Romrell]

I frequently don't like the use of "rise" here on DFP when determined whether a pitch is a riseball or not. I would ask, "Rises relative to what?" It may end up higher, when caught, than the height it was released at, but it doesn't "rise" above it's initial trajectory. We all understand that a drop ball, or any other pitch for that matter, can end up higher than the height it was released at, but drops a great deal from initial trajectory. The batter could be fooled into thinking this pitch will end up way to high, only to have it drop into the top end of the strike zone. We also understand that any pitch, including a "riseball" (good backspin and good velocity) can be released too early such that it ends up being caught lower than its release height. The batter could be fooled into thinking this pitch will end up way too low, only to have it end up in the bottom of the strike zone, because it didn't fall as much as the batter thought it would.

So is a dropball that ends up being caught above the height of its release a riseball? I say, "Of course not."
Is a riseball (good backspin good velocity) that ends up being caught below the height of its release a dropball? I say, "Of course not."

The pitch that holds closer to its original trajectory is a ball thrown with good backspin (including backspin with a tilted axis) and good velocity. I think this is what we should call a "riseball" regardless of where it ends up. Why? Because it will give the appearance of rising above initial trajectory because it falls less than all the other pitches. And, a pitch that is thrown with topspin (even with a tilted axis)..... I think it should be called a dropball ball regardless of where it ends up. Why? Because it will drop the most from its initial trajectory, giving the appearance (relative to a pitch with backspin) of really dropping, even if thrown higher.

 

[riseball]

This is all interesting but it seems much more about theory than real world observations. I would be interested to find out how is the launch angle was determined. Also, in addition to spin rate how is the orientation of the ball with respect to roll, pitch, and yaw which all affect movement taken into account? It would also be interesting to understand an accounting of the affect of drag with respect to the aforementioned.

 

[pobguy]

This is all interesting but it seems much more about theory than real world observations. I would be interested to find out how is the launch angle was determined. Also, in addition to spin rate how is the orientation of the ball with respect to roll, pitch, and yaw which all affect movement taken into account? It would also be interesting to understand an accounting of the affect of drag with respect to the aforementioned.

Agreed! And as I already said, the point is not to predict with precision but to demonstrate the qualitative effects. On the other hand, the technology now exists to obtain precise data on the trajectories of pitched baseballs or softballs in actual game situations. One such technology is the so-called Trackman radar system, which is used in many MLB stadiums and some NCAA games. It is less used in fastpitch softball, but it certainly could be used. The system provides full information on the trajectory of each pitch, including release speed, height, and angles, home plate crossing (including speed and direction), spin rate, and spin axis. In short, it pretty much provides everything you would want to know about the pitch from release to home plate.

There is also so-called PITCHf/x system, which uses cameras to track the ball and is installed in every MLB ballpark. It too provides full information on the ball's trajectory. However unlike Trackman, the spin rate is not directly measured; instead it is estimated from the amount of movement. Still, it is a useful estimate. I managed to get a full set of tracking data from the 2011 WCWS (I referred to this earlier in this thread) and gave a short presentation on it back then. You can get some appreciation of the information it provides by looking at the presentation: http://baseball.physics.illinois.edu/ppt/NathanWCWS.ppt.

 

[Easton33]

The NASA calculations and my own are not so different. There might be small differences due to different assumptions about the air drag, since there can be variations in drag due to temperature, elevation, surface roughness of ball, etc. I guarantee that if air drag were eliminated, we would all get exactly the same trajectory for the gravity-only case. That is a calculation that is done by week 2 of an introductory physics course.

However, one should not focus on the differences in these different calculations but rather their similarities. The point of these calculations is *not* to predict with precision the trajectory of the ball but rather to demonstrate the qualitative effects that occur due to backspin, topspin, etc. For example, these calculations clearly show that a rise ball really can rise, meaning it crosses the plate above the release point. Also they show that for any reasonable amount of spin, the trajectory never rises above the projection of the initial direction (the red line in my graphs). The calculations show that the height of the ball as it crosses the plate is very sensitive to the release angle of the pitch, regardless of the spin axis. The calculations also show that the ball drops more with topspin than with gravity alone. These are all useful things to know and understand, at least at the qualitative level.

So you are using a different set of variables vs what the NASA calculator is using, ok. If you will go back to Sluggers post, you are actually at odds with what he is saying. Not only are the numbers off, (1' difference at 40' is huge) but he clearly states a rise ball does not rise it just falls less. In this post you say it does in fact rise. I am not giving you a hard time here, I am just saying that the numbers presented were stated as fact but they aren't and even though you and Sluggers appear to be in agreement, you aren't. Or at least the way the information was presented it appears you aren't.

 

[JJsqueeze]

When POBGUY says it rises he just means it ends up at a higher spot than it began but the path is not considered. He also clearly state that it NEVER rises above the initial trajectory. So a ball thrown with a slow pitch arc from the pitchers hip but comes into the batter shoulder high would RISE with this definition, but of course no one would call it a rise ball.

 

[pobguy]

So you are using a different set of variables vs what the NASA calculator is using, ok. If you will go back to Sluggers post, you are actually at odds with what he is saying. Not only are the numbers off, (1' difference at 40' is huge) but he clearly states a rise ball does not rise it just falls less. In this post you say it does in fact rise. I am not giving you a hard time here, I am just saying that the numbers presented were stated as fact but they aren't and even though you and Sluggers appear to be in agreement, you aren't. Or at least the way the information was presented it appears you aren't.

If I interpret correctly what Sluggers is saying about "rise", we do not disagree. His examples were for a ball released horizontally. For such a ball, he states that the ball cannot rise. I completely agree with that. My generalization of his statement is the following: regardless of the release angle, the ball does not rise above the extension of that direction. In the graphs I posted, that extension is the red line.

However, you are correct that we differ by about 1 ft in the amount of drop on a ball thrown horizontally without spin. And I agree that that amount of disagreement is not acceptable. I can only comment on my own calculation. As I said, w/o air drag, the calculation is pretty simple; I just did it and got a drop of 3.3 ft. My calculation with drag got 3.5 ft. The drag slows the ball down, giving gravity more time over which to act (therefore, more drop). It's hard (for me) to see how a different assumption about drag could change the drop by 1 ft. I am not trying to be critical of anyone here, only responding to the question you raised.

 

[Otto]

Can of worms time!

I guess Javasource nailed it back in post #3.