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Rising fastball

  1. May 12, 2006 #1
    I have a rather simple question for the minds who paruse this forum. My question is this. Can a baseball thrown overhand by a human being by provided with enough backspin for it to escape it's initial velocity vector, and in fact actually rise as it approaches the plate?

    Thank you,

  2. jcsd
  3. May 12, 2006 #2
    Considering that professional baseball players do not throw 'riser' balls, I'm inclinded to say no. If they could do it, the most probably would.
  4. May 14, 2006 #3
    A "drop ball" requires a backspin, which is not hard for a pitcher to impart.
    However, a "riser" ball rquires a forward spin, and this type of spin is not easy to impart with an overhand throw.
    An underhand pitch will favor forward spin, but the ball velocity potential is lower than overhand pitching, and accuracy is lower, so it is not used in regular pro-baseball.

    One COULD do a reverse-grip overhand throw, resulting in a "riser-ball"
    This entails holding the baseball inwards towards the pitcher instead of outwards during release.
    This would effect a forward spin from a overhand throw.
    However, this has problems.
    The reverse-grip release uses muscles of the arm which are much weaker than muscles used to create the backspin of a drop or curve ball.
    Also, the finger positions around the ball in a reverse-grip do not tend to favor imparting maximum spin as opposed to normal-grip.
    The "across-the-plate" accuracy of this technique is actually lower than that of an underhand throw.

    So, is it possible? Yes.
    Will a "riser-ball" dramatically shift as much as a drop-ball? No. The velocity and spin potentials are lower due to human physiology.
    Will a "riser-ball" ever make it into pro-baseball? Perhaps, but not likely. It's slower, inaccurate and does not exhibit an appreciable effect.
  5. May 14, 2006 #4


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    Having been a slow-pitch player back in the day, I'd have to agree with Palladin. Due to a congenital shoulder malformation, I can't throw overhand. Sidearm is the best that I can manage, and even that hurts. Where I disagree to some extent is the relative power between under/over. While I was not a serious fastball pitcher, I could windmill underhand a ball just about as hard as most people could throw overhand. Professional fastball pitchers can get to around 90mph. It's not all that difficult to throw a riser when you can get the speed.
  6. May 15, 2006 #5


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    Just the opposite, a riser requires backspin, and a sinker requires top spin. Tennis and table tennis players use top spin to get the ball to curve downwards and land in court in spite of high velocities and being struck upwards from below the net.

    Part of the issue with hardball (pro baseball) is the pitcher is throwing downwards from an elevated mound, with overhead motion, so the ball has to travel 5 or 6 feet downwards from the release point to reach the strike zone. I've read that about 3 feet of this drop is due to gravity. A riser may only drop 2 feet due to gravity. I don't know if a hardball thrown and released horizontally could rise.

    In the case of softball, the strike zone is about the same height as the release point. Softballs have bigger seams, so a true riser might be possible.

    Table tennis is probably involves the most extreme amount of curving of the ball during play. Good table tennis rubber has a high amount of elacticity (over 85%), and a high amount of friction (coeffiecient of friction well over 5), so there's a huge amount of spin involved. A true riser can be thrown with a table tennis ball, and when struck with a paddle, it's even more extreme. Sample video of the grip and small amount of motion it takes to keep alternating the spin on a ball, then a video of a few points by former world champ Jan Waldner from Sweden.


    Last edited: May 15, 2006
  7. May 15, 2006 #6


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    HA! My Dad played fast pitch back in the day. It used to drive me crazy when he would zing a ball at me from the hip. Damn he could throw a ball too.

    However, looking at the lift forces on a ball as it is flying, the lift, [tex]F_y[/tex] after all of the hand waving is essentially

    [tex]F_y = -\rho u \Gamma[/tex] where
    [tex]F_y[/tex] = Lifting force
    [tex]\rho[/tex] = density
    [tex]\Gamma[/tex] = circulation (vortex strength)

    Because of the negative sign, if one has a u in the positive X direction with a circulation that is positive (CCW), a negative [tex]F_y[/tex] is produced and the ball drops. Looking at a baseball when it is pitched, this makes sense since the pitcher always imparts backspin and the ball always drops. I'm going to have to think through the ping pong ball though because personal experience agrees there that top spin makes the ball drop as well.
    Last edited: May 15, 2006
  8. May 15, 2006 #7


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    Jeff Reid is right, both on the spin and the phenomenom. A 'riser' doesn't actually rise. It just defies the trajectory that a batter has observed for his entire life.

    The way humans perceive things can be a little deceiving. People learn physics by experience and have a difficult time figuring out why an object didn't behave quite the way it was supposed to - just like a power shot in soccer with no spin feels heavier than a shot that has some spin. The spin is providing the keeper with a lot of information on how the ball will behave, plus allows the ball to resist some of the minor variations in air density, wind speed, etc. With no spin, the ball's affected more by its environment and the keeper doesn't have enough information to quite anticipate when the ball will reach his hands, hence the heavier feel to the shot.
  9. May 15, 2006 #8


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    Are you watching the trajectory from the first base side or the third base side?

    If the ball were travelling perfectly horizontal, the forces created by the back of the ball and the front of the ball would be equal regardless of spin. With backspin, the seams on the bottom of the ball would encounter greater resistance than the seams on the top of the ball. This would create lift. I don't think a human could create enough lift to overcome the force of gravity - the ball will always be falling.

    With backspin, the seams on the back of the ball are pushing down against the air. Since the ball is falling, the seams encounter a greater resistance than if the ball were travelling perfectly horizontal. The seams on the front of the ball are pushing up against the air. Since the ball is falling, the seams are encountering less resistance. The backspin is creating a greater upward force than downward force, creating more lift.

    If the ball were truly rising, the front of the ball would create a greater downward force than the upward force created by the back of the ball.
  10. May 15, 2006 #9
    Anybody who plays golf will have seen their ball rising due to backspin.

    "Spin rate plays a major role in how long the golf ball will stay in the air. A player that produces too low a spin rate will find the golf ball going lower and coming down very quickly. A player with too high a spin rate will find the golf ball rising very high and have a ballooning effect..."
  11. May 15, 2006 #10


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    Hi, Bob;
    I was kind of wondering if there might be an illusional effect involved. My dad was a hardball pitcher and catcher back in the 1910-1950 range. He told me that a 'floater' or 'knuckleball' is thrown with no spin at all. Even though it flies at almost the same speed as a regular pitch, the fact that the batter can see the seams not rotating leads him to think that it's much slower. (By the way, I saw a study somewhere that proved that a batter can't track a hardball all the way from the pitcher. He has to either watch it leave the pitcher's hand and then extrapolate the trajectory, or wait and pick it up when it gets close. The ball travels faster than the eye can refocus.)
  12. May 15, 2006 #11


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    Last edited: May 15, 2006
  13. May 15, 2006 #12


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    I agree, and I disagree with the wikipedia saying that it is "impossible" for a rising fastball to be thrown. Maybe the aerodynamics are too compromised for a baseball compared to a golf ball -- but it would be interesting to see the proof.

    For sure the effect of a well-thrown baseball not falling as much as expected is very real. We used it on my highschool baseball team, and pro players use it all the time. You end up throwing ropes from the outfield or across the diamond that drop very little, until they start to run out of spin rate. It's a cool trick to teach young ball players -- learn to always pull the ball out of your glove with your fingertips across the seams (this takes some practice), and add a strong wrist snap down when you throw. It's really fun to throw ropes!
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