# What's the fastest moving body part? **URL:** \ **Category:** Factual Questions\ **Created:** [October 19, 2012, 2:17pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227 "2012-10-19T14:17:19Z")\ **Posts on this page:** 13\ **Page:** 3
**Author:** ![getitrite](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@getitrite](https://boards.straightdope.com/u/getitrite)\ **Post date:** [October 22, 2012, 5:33pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/41 "2012-10-22T17:33:16Z")
The fastest human foot speed is 27.79 mph for 100 meters, Measuring the speed of the ball that is thrown does not satisfy the op, and the hand transfers the energy to the ball for the fast pitch. ---
**Author:** ![TruCelt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/trucelt/32/523_2.png) [@TruCelt](https://boards.straightdope.com/u/TruCelt)\ **Post date:** [October 22, 2012, 5:55pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/42 "2012-10-22T17:55:13Z")
What about the contraction of the Iris when a bright light is introduced? ---
**Author:** ![Disheavel](https://avatars.discourse-cdn.com/v4/letter/d/e274bd/32.png) [@Disheavel](https://boards.straightdope.com/u/Disheavel)\ **Post date:** [October 22, 2012, 6:04pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/43 "2012-10-22T18:04:58Z")
> [@jasg](#): > > A few years later, many embarrassed Jr High school boys would vote for another part of their anatomy 😃 I think you meant “vote WITH another part of their anatomy”. ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [October 22, 2012, 6:09pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/44 "2012-10-22T18:09:38Z")
> [@getitrite](#): > > Measuring the speed of the ball that is thrown does not satisfy the op, and the hand transfers the energy to the ball for the fast pitch. Maybe I’m crazy, but that doesn’t make any sense to me. Think of it this way. 1. When two things are touching each other and not moving in relation to one another, they are by definition going to same speed. This is the end of the pitcher’s fingers and the ball. 2. The ball must be going it’s maximum speed before or at the instant of its release. Once it is released, it will only slow down due to air friction. If the ball is clocked at moving 100mph, then some part of the pitcher’s fingers must be going that speed. ---
**Author:** ![standingwave](https://avatars.discourse-cdn.com/v4/letter/s/9de0a6/32.png) [@standingwave](https://boards.straightdope.com/u/standingwave)\ **Post date:** [October 22, 2012, 6:19pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/45 "2012-10-22T18:19:57Z")
> [@WhyNot](#): > > No way. Takes several hours for most sperm to make it several inches to the fallopian tubes. > > ~28mph. Impressive, but not mindblowing It’s also beaten out by a human cough which can expel aerosolized gunk at over 60mph. ---
**Author:** ![Evil\_Economist](https://avatars.discourse-cdn.com/v4/letter/e/c89c15/32.png) [@Evil\_Economist](https://boards.straightdope.com/u/Evil_Economist)\ **Post date:** [October 22, 2012, 7:12pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/46 "2012-10-22T19:12:47Z")
I was told by a sport scientist that the pull-under in the snatch (olympic lift) is the fastest full-body movement in sports. I searched around just now and found a [cite](http://drsquat.com/content/knowledge-base/athletes-and-olympic-lifts): > [@](#): > > Getting under the bar occurs much faster than gravity allows, because the lifters are actually pulling themselves under the bar. In fact, the snatch and clean movements – getting under the bar – are measurably the fastest total body movements that exist in all sport. Provided, that is, it’s being demonstrated by an elite lifter. ---
**Author:** ![lisiate](https://avatars.discourse-cdn.com/v4/letter/l/f05b48/32.png) [@lisiate](https://boards.straightdope.com/u/lisiate)\ **Post date:** [October 22, 2012, 7:59pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/47 "2012-10-22T19:59:05Z")
> [@Pitchmeister](#): > > Not a voluntary muscle movement either. The vocal chords vibrate because of the air being pushed through them by the lungs. We mereley control the air flow and the tension of the vocal chords. Awesome post/user name combo. I was going to suggest the vocal chords too, but they’re out of the running. ---
**Author:** ![Condescending\_Robot](https://avatars.discourse-cdn.com/v4/letter/c/a183cd/32.png) [@Condescending\_Robot](https://boards.straightdope.com/u/Condescending_Robot)\ **Post date:** [October 22, 2012, 8:23pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/48 "2012-10-22T20:23:11Z")
> [@Hermitian](#): > > 1. When two things are touching each other and not moving in relation to one another, they are by definition going to same speed. This is the end of the pitcher’s fingers and the ball. But they are moving in relation to one another. The arm and hand are moving in an elliptical path, and the ball is released on a tangent straight path. The transfer of the energy necessary to accelerate the 200-lb pitcher in a circular path to the five-ounce baseball moving linearly is exactly why a human being who can never move at 100 mph can make a baseball do so. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [October 22, 2012, 9:46pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/49 "2012-10-22T21:46:34Z")
> [@Condescending\_Robot](#): > > But they are moving in relation to one another. The arm and hand are moving in an elliptical path, and the ball is released on a tangent straight path. The transfer of the energy necessary to accelerate the 200-lb pitcher in a circular path to the five-ounce baseball moving linearly is exactly why a human being who can never move at 100 mph can make a baseball do so. Sincerely, and not to be snarky, so what? **Hermitian’s** point, which makes sense to me, is that at the moment of release the ball is going 100 mph and thus the fingertip touching and propelling it must also be going that speed, even if only for an instant. Whatever the path and speed of the fingertips – and the ball they’re holding – prior to that moment don’t change the fact that for that particular moment they’re moving at the same speed. Is that not right? ---
**Author:** ![Condescending\_Robot](https://avatars.discourse-cdn.com/v4/letter/c/a183cd/32.png) [@Condescending\_Robot](https://boards.straightdope.com/u/Condescending_Robot)\ **Post date:** [October 22, 2012, 9:54pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/50 "2012-10-22T21:54:32Z")
> [@Gary\_T](#): > > Sincerely, and not to be snarky, so what? **Hermitian’s** point, which makes sense to me, is that at the moment of release the ball is going 100 mph and thus the fingertip touching and propelling it must also be going that speed, even if only for an instant. Whatever the path and speed of the fingertips – and the ball they’re holding – prior to that moment don’t change the fact that for that particular moment they’re moving at the same speed. Is that not right? The “same speed” with respect to what? The pitcher’s arm isn’t moving in a straight line towards home plate (baseballs don’t get thrown like shotputs and shotputs don’t move at 100 mph). What is the meaning of comparing rotational velocity with linear velocity and then saying they are or must be “the same?” ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [October 22, 2012, 9:58pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/51 "2012-10-22T21:58:05Z")
> [@Condescending\_Robot](#): > > The “same speed” with respect to what? The pitcher’s arm isn’t moving in a straight line towards home plate (baseballs don’t get thrown like shotputs and shotputs don’t move at 100 mph). What is the meaning of comparing rotational velocity with linear velocity and then saying they are or must be “the same?” The linear velocity of the finger tips is 100 mph with respect to the ground upon which the pitcher is standing. One foot of the picture is not moving with respect to the ground. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [October 22, 2012, 9:58pm UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/52 "2012-10-22T21:58:07Z")
> [@Gary\_T](#): > > Sincerely, and not to be snarky, so what? **Hermitian’s** point, which makes sense to me, is that at the moment of release the ball is going 100 mph and thus the fingertip touching and propelling it must also be going that speed, even if only for an instant. Whatever the path and speed of the fingertips – and the ball they’re holding – prior to that moment don’t change the fact that for that particular moment they’re moving at the same speed. Is that not right? Not if the ball ‘rolls’ against the fingers before release, the ball can still be accelerated and energy transfered to the ball beyond the motion of the hand/fingers. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [October 23, 2012, 2:00am UTC](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227/53 "2012-10-23T02:00:59Z")
> [@Condescending\_Robot](#): > > But they are moving in relation to one another. The arm and hand are moving in an elliptical path, and the ball is released on a tangent straight path. The transfer of the energy necessary to accelerate the 200-lb pitcher in a circular path to the five-ounce baseball moving linearly is exactly why a human being who can never move at 100 mph can make a baseball do so. Are you saying the whole body has to be moving for it to count? That wouldn’t work, since it’s easy to accelerate the whole body, like in vehicles or even a moving observer. Speed has to be relative to the rest of the body. [Previous page](https://boards.straightdope.com/t/whats-the-fastest-moving-body-part/638227.md?page=2)