# Re the velocity of a pitched baseball: Does the pitcher's arm speed equal the baseball's velocity? **URL:** \ **Category:** Factual Questions\ **Created:** [October 26, 2012, 11:27am UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916 "2012-10-26T11:27:28Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Deadhead\_Dave](https://avatars.discourse-cdn.com/v4/letter/d/838e76/32.png) [@Deadhead\_Dave](https://boards.straightdope.com/u/Deadhead_Dave)\ **Post date:** [October 26, 2012, 11:27am UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/1 "2012-10-26T11:27:28Z")
Watching the World Series last evening, my kids and I had a dispute about what determines the speed of a pitched baseball. For a baseball to be thrown one hundred miles per hour, is the pitcher’s arm rotating / travelling at one hundred miles per hour just before the ball is released? What say you, physics gods? (Mods - feel free to move this). ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [October 26, 2012, 11:37am UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/2 "2012-10-26T11:37:00Z")
The pitcher’s \*hand \*has to be rotating at 100mph, not his entire arm. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [October 26, 2012, 11:51am UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/3 "2012-10-26T11:51:30Z")
The pitcher’s fingers must reach whatever speed the ball is going to be travelling at. The last part of the fingers that propels the ball determines its ultimate velocity. The farthest point along the fingers is moving the fastest. The ball can’t go faster than this. . ---
**Author:** ![AK84](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@AK84](https://boards.straightdope.com/u/AK84)\ **Post date:** [October 26, 2012, 11:53am UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/4 "2012-10-26T11:53:37Z")
The muscles in a pitchers (or a cricket bowlers for that matter) arm and shoulder have to deliver to the ball force which would take it to an acceleration which would cause it to exceed 100 mph in speed at the point when the speedgun takes the measurements. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [October 26, 2012, 12:00pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/5 "2012-10-26T12:00:50Z")
Right, so it may have to be moving significantly faster but never slower. ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [October 26, 2012, 12:17pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/6 "2012-10-26T12:17:57Z")
Think of the ball being an extension of the pitcher’s arm. It is the end point right up until the release. The action is designed to get this part of the arm travelling at the highest possible speed. (rather like the tip of a whip) and from that point on it is decelerating. ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [October 26, 2012, 12:21pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/7 "2012-10-26T12:21:03Z")
> [@Richard\_Pearse](#): > > Right, so it may have to be moving significantly faster but never slower. If you are talking about the last part of the arm in contact with the ball then yes. However, various parts of the arm may well be moving more slowly than the ball at point of release (again…the whip analogy, Indiana’s whole arm does not break the speed of sound) ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [October 26, 2012, 12:48pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/8 "2012-10-26T12:48:01Z")
Whip analogy is misleading. The ball is not reacting as the whip does. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 26, 2012, 12:53pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/9 "2012-10-26T12:53:08Z")
Actually, I was thinking about this since the previous thread, and it is possible in some circumstances for the speed of a thrown object to exceed the speed of any part of the body that threw it. The simplest example would be squeezing a watermelon seed between one’s fingers: The speed at which the seed is shot out is greater than the speed of the fingers squeezing it. If, at the moment of release, the ball is rolling along the pitcher’s fingers, a fastball might be another such case (though obviously, through a different mechanic). ---
**Author:** ![anson2995](https://avatars.discourse-cdn.com/v4/letter/a/c77e96/32.png) [@anson2995](https://boards.straightdope.com/u/anson2995)\ **Post date:** [October 26, 2012, 1:44pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/10 "2012-10-26T13:44:27Z")
A great source for understanding this and similar questions is [the work of Alan Nathan](http://webusers.npl.illinois.edu/~a-nathan/pob/). He’s a prof at the University of Illinois whose research is focused on the physics of baseball. He’s got some great videos on his website. ---
**Author:** ![Malden\_Capell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/malden_capell/32/5274_2.png) [@Malden\_Capell](https://boards.straightdope.com/u/Malden_Capell)\ **Post date:** [October 26, 2012, 1:45pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/11 "2012-10-26T13:45:22Z")
Which do you mean? African or European? ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [October 26, 2012, 2:57pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/12 "2012-10-26T14:57:35Z")
> [@Philster](#): > > Whip analogy is misleading. > > The ball is not reacting as the whip does. In what way misleading? In terms of acceleration the ball at the end of the arm is analogous to the tip of the whip. ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [October 26, 2012, 4:35pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/13 "2012-10-26T16:35:22Z")
If there were a strong enough wind blowing in the direction the ball was traveling, I suppose it’d be at least theoretically possible for it to pick up speed after it left the pitcher’s hand. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [October 26, 2012, 4:40pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/14 "2012-10-26T16:40:07Z")
> [@Thudlow\_Boink](#): > > If there were a strong enough wind blowing in the direction the ball was traveling, I suppose it’d be at least theoretically possible for it to pick up speed after it left the pitcher’s hand. Only if the game wasn’t called due to hurricane. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [October 26, 2012, 5:03pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/15 "2012-10-26T17:03:01Z")
A related question is can the ball be going faster than the point on the bat that it strikes? Well, the answer to that is yes, which is obvious from the fact that if we throw it into a brick wall, it bounces off. In theory, the same could be true of the pitcher’s hand, but in practice, I doubt it very much. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [October 26, 2012, 10:47pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/16 "2012-10-26T22:47:08Z")
> [@Learjeff](#): > > In theory, the same could be true of the pitcher’s hand… I suspect a pitch that bounced off the pitcher’s hand would fall foul of some obscure rule. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [October 27, 2012, 1:56am UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/17 "2012-10-27T01:56:32Z")
> [@Thudlow\_Boink](#): > > If there were a strong enough wind blowing in the direction the ball was traveling, I suppose it’d be at least theoretically possible for it to pick up speed after it left the pitcher’s hand. I think the wind would have to be going faster than the ball; otherwise it would merely slow the ball’s deceleration due to air resistance. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [November 1, 2012, 6:20pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/18 "2012-11-01T18:20:18Z")
> [@Xema](#): > > I suspect a pitch that bounced off the pitcher’s hand would fall foul of some obscure rule. It doesn’t have to “bounce” in the sense of leaving the hand and then being struck by it. If it were possible to, at the end of the pitch, impel the ball with the fingers enough to deform it (by acceleration of the hand or parts of the hand), that would be enough and wouldn’t run afoul of any rules. But I’m skeptical that anything like this is actually possible in a real pitch. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [November 1, 2012, 6:46pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/19 "2012-11-01T18:46:33Z")
> [@Novelty\_Bobble](#): > > In what way misleading? In terms of acceleration the ball at the end of the arm is analogous to the tip of the whip. Because the whip is building up energy since it’s extremely flexible and also extended. The ball? Not in any measurable or meaningful way. For purposes of this discussion, the ball is rigid. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 1, 2012, 8:13pm UTC](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916/20 "2012-11-01T20:13:39Z")
You could also roll the ball along your hand as your throwing it, using your hand sort of like a jai alai scoop. [Next page](https://boards.straightdope.com/t/re-the-velocity-of-a-pitched-baseball-does-the-pitchers-arm-speed-equal-the-baseballs-velocity/638916.md?page=2)