# The puzzle of the bee and the train **URL:** \ **Category:** Factual Questions\ **Created:** [October 6, 2008, 4:55pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696 "2008-10-06T16:55:17Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [October 10, 2008, 12:52am UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/61 "2008-10-10T00:52:16Z")
> [@scottie](#): > > So, the conundrum remains unaswered. Frankly it has been answered upwards downwards and sideways, about six times over, using example after example after analogy. You just don’t get it and at this stage if I were you I’d consider resigning myself to the fact I wasn’t going to get it. There’s not much point in explaining it all to you yet again. ---
**Author:** ![laughingboy](https://avatars.discourse-cdn.com/v4/letter/l/9f8e36/32.png) [@laughingboy](https://boards.straightdope.com/u/laughingboy)\ **Post date:** [October 10, 2008, 1:27am UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/62 "2008-10-10T01:27:02Z")
> [@chacoguy420](#): > > Now, play nice with the guest. Or what? You’ll release the dogs, or the bees, or the dogs with bees in their mouths, and when they bark, they shoot bees at you? This is the Simpsons quote thread, right? ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [October 10, 2008, 2:38pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/63 "2008-10-10T14:38:22Z")
> [@Giles](#): > > Well, the bee squashes up a lot, so I’m not convinced that it ever travels faster than the train. But if you had a steel ball bearing about the same size (volume or mass, it doesn’t really matter much) hitting the steel front of the train, it would bounce off the front, travelling at roughly twice the speed of the train. (The energy for this coming from the train slowing just just a tiny amount). I think the majority of the train remains constant. Just a microscopic portion slows a tiny amount. ---
**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\ **Post date:** [October 10, 2008, 3:01pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/64 "2008-10-10T15:01:14Z")
> [@Hampshire](#): > > I think the majority of the train remains constant. Just a microscopic portion slows a tiny amount. Suppose the ball weighs 10 g, and the train weighs 1,000 tons, i.e., 1 billion g. Then the train will slow down from 80 mph (i.e., about 35 m/s) by about 0.000 000 35 m/s. Not enough to be detectable, but enough to be calculable. ---
**Author:** ![glee](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@glee](https://boards.straightdope.com/u/glee)\ **Post date:** [October 10, 2008, 3:18pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/65 "2008-10-10T15:18:37Z")
I wanted to make a beeline for this thread, because I’m trained that way. So I don’t lose track, let me add that my physics textbook in school described the energy needed to stop something using these two examples: - stopping a bullet (light, but fast) - stopping a ship (heavy but slow) Which leads me to speculate that, provided the train is freewheeling along a flat track (slowing gently due to friction + air resistance), a \*\*massive \*\*swarm of bees all hitting it in succession could stop it. ---
**Author:** ![Nancarrow](https://avatars.discourse-cdn.com/v4/letter/n/c37758/32.png) [@Nancarrow](https://boards.straightdope.com/u/Nancarrow)\ **Post date:** [October 10, 2008, 6:26pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/66 "2008-10-10T18:26:10Z")
> [@CurtC](#): > > Yes, this is true. The closest that the bee can ever get is 0.9999999… of the initial distance, and this will never equal one. Oh, come ON. You might have a point if the bee was on a treadmill. Or if it wasn’t a bee, but was an insect whose specific name ends in ‘gry’. But as it is you’re just being silly. ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [October 10, 2008, 6:28pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/67 "2008-10-10T18:28:28Z")
I think it is worth noting that a lot of attention seems to be being paid to what happens “at speed zero”, or"when it passes through zero" as if it has some special significance, but it does not. Change the problem to a hovering bee is struck by a train traveling at 83 mph. What’s happening when the bee is traveling at 3mph? ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [October 10, 2008, 8:05pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/68 "2008-10-10T20:05:48Z")
> [@Princhester](#): > > … you are talking about two things being in contact while not moving at the same speed, which (a) is clearly an oxymoron … How is this an oxymoron? If I have two blocks sliding past each other in opposite directions, are you claiming they aren’t really in contact, or not really travelling in opposite directions? ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 8:49pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/69 "2008-10-10T20:49:21Z")
I got this and I was right. The trick is to realize that at the atomic level there are no inelastic collisions and everything is action-at-a-distance. A classical model would need a tiny fictitious spring connecting every microscopic particle of the two bodies. Now do the math and bow before me you puny humans. 😛 ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 9:01pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/70 "2008-10-10T21:01:53Z")
> [@Pedro](#): > > A classical model would need a tiny fictitious spring connecting every microscopic particle of the two bodies. …At the level where electromagnetic forces overwhelm the gravitational force of course. (Missed the edit window.) ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 9:24pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/71 "2008-10-10T21:24:02Z")
> [@Mangetout](#): > > If there were no elasticity in the coupling, this would not be possible - that was my point. Yes it would. Does a car reverse direction when braking? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 10, 2008, 9:33pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/72 "2008-10-10T21:33:35Z")
> [@Pedro](#): > > Yes it would. Does a car reverse direction when braking? You’re saying it would be possible without elasticity in the coupling between bee and train? I disagree. It must take time for the bee - or parts thereof - to reverse direction. At the moment when this has only just begun to happen, if the bee parts are non-elastically coupled to the train parts, they can’t be doing different things - so part of the train _would have to be_ travelling backwards, in the direction of the adjoined bee parts. You appear to have acknowledged this to other posters above - why are you still arguing it with me? ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 9:42pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/73 "2008-10-10T21:42:48Z")
> [@Mangetout](#): > > You’re saying it would be possible without elasticity in the coupling between bee and train? I disagree. That it is possible for the acceleration to flip signal while maintaining positive velocity without elasticity, yes, which it seemed you were arguing against. But maybe I misunderstood again. > [@](#): > > It must take time for the bee - or parts thereof - to reverse direction. At the moment when this has only just begun to happen, if the bee parts are non-elastically coupled to the train parts, they can’t be doing different things - so part of the train _would have to be_ travelling backwards, in the direction of the adjoined bee parts. Did you read my reply above about action-at-a-distance? > [@](#): > > You appear to have acknowledged this to other posters above - why are you still arguing it with me? I have re-reversed my position, it’s nothing personal. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 10, 2008, 9:59pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/74 "2008-10-10T21:59:58Z")
Action at a distance is a form of elastic coupling - unless you’re specifically claiming it to be rigid (which I’m sure would just be wrong) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 10, 2008, 10:02pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/75 "2008-10-10T22:02:01Z")
> [@Pedro](#): > > That it is possible for the acceleration to flip signal while maintaining positive velocity without elasticity, yes, which it seemed you were arguing against. But maybe I misunderstood again. The what? Macroscopic physical objects cannot reverse direction instantaneously, or without stopping in the middle of the process. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 10:52pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/76 "2008-10-10T22:52:39Z")
> [@Mangetout](#): > > Action at a distance is a form of elastic coupling - unless you’re specifically claiming it to be rigid (which I’m sure would just be wrong) So are you still saying a part of the train must stop or not? > [@Mangetout](#): > > The what? Macroscopic physical objects cannot reverse direction instantaneously, or without stopping in the middle of the process. You must think me a real dimwit. Forget this tangent, we seem to be talking at cross-purposes. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 10, 2008, 10:55pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/77 "2008-10-10T22:55:01Z")
> [@Pedro](#): > > So are you still saying a part of the train must stop or not? Only in a scenario where the objects were absolutely rigid and capable of making absolutely inelastic contact. Neither of which is possible in reality, so… no. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 11:05pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/78 "2008-10-10T23:05:04Z")
> [@Mangetout](#): > > Only in a scenario where the objects were absolutely rigid and capable of making absolutely inelastic contact. Neither of which is possible in reality, so… no. No what? The mistake the posters I argued against did (and me, at some point) is thinking the classical inelastic collision model applies to (non-ideal) non-rigid objects. It does not. The train and fly are never in contact microscopically. Are you following this? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 10, 2008, 11:16pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/79 "2008-10-10T23:16:29Z")
> [@Pedro](#): > > No what? No, in answer to your question: “So are you still saying a part of the train must stop or not?” > [@](#): > > The mistake the posters I argued against did (and me, at some point) is thinking the classical inelastic collision model applies to (non-ideal) non-rigid objects. It does not. The train and fly are never in contact microscopically. Are you following this? Following it? It’s what I’ve been saying all along. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [October 10, 2008, 11:24pm UTC](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696/80 "2008-10-10T23:24:32Z")
> [@Mangetout](#): > > No, in answer to your question: “So are you still saying a part of the train must stop or not?” That would be “not” then. Great, we agree. [QUOTE=Mangetout] Following it? It’s what I’ve been saying all along. [/QUOTE] Yeah, I don’t think so, since you also said this in post #40: [QUOTE=Mangetout] Parts of the system will have to reverse direction momentarily, no matter what, because the parts of the bee can’t reverse velocity without going through zero. [/QUOTE] But whatever. [Previous page](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696.md?page=3) [Next page](https://boards.straightdope.com/t/the-puzzle-of-the-bee-and-the-train/466696.md?page=5)