极限摩擦实验，结果出乎意料
字幕摘录
| 时间 | 英文 | 中文 |
|---|---|---|
| 0:00 | Today I decided to teach my kids about friction, the action lab boy. | 今天我决定教孩子们摩擦 动作实验室男孩 |
| 0:11 | This might look impossible, but right now static friction is holding him against the wall. | 这看起来可能是不可能的,但现在静态摩擦正把他拖到墙上。 |
| 0:16 | After I successfully held the younger kids, I decided to try my oldest, who's now bigger than me. | 在我成功抚养了年幼的孩子之后,我决定尝试我最年长的,现在比我大. |
| 0:21 | If static friction really works the way physics says it should, I should be able to hold him up. | 如果静电摩擦真的像物理学上说的一样有效,我应该能够扶住他. |
| 0:26 | I think. | 我觉得 |
| 0:27 | In this video, I'm going to show you why it seems so easy to hold someone up against a wall. | 在这段视频中,我要告诉你为什么把一个人抱在墙上看起来那么容易. |
| 0:32 | In discussing this, we'll run into one of the deepest mysteries in physics, | 在讨论这个问题时,我们会遇到物理学中最深奥的谜题之一, |
| 0:35 | where the equations become undefined and even paradoxical in basic friction problems. | 在基本摩擦问题上,方程式变得不明确甚至自相矛盾。 |
| 0:41 | And then we'll see if I was able to successfully hold my son up. | 然后再看看我能不能成功地抱住我儿子 |
| 0:44 | But before we continue, I want to tell you about the sponsor for this video, Lien. | 但是在我们继续之前 我想告诉你这段视频的赞助商 Lien |
展开字幕全文（136 条）
| 序号 | 英文 | 中文 |
|---|---|---|
| 1 | Today I decided to teach my kids about friction, the action lab boy. | 今天我决定教孩子们摩擦 动作实验室男孩 |
| 2 | This might look impossible, but right now static friction is holding him against the wall. | 这看起来可能是不可能的,但现在静态摩擦正把他拖到墙上。 |
| 3 | After I successfully held the younger kids, I decided to try my oldest, who's now bigger than me. | 在我成功抚养了年幼的孩子之后,我决定尝试我最年长的,现在比我大. |
| 4 | If static friction really works the way physics says it should, I should be able to hold him up. | 如果静电摩擦真的像物理学上说的一样有效,我应该能够扶住他. |
| 5 | I think. | 我觉得 |
| 6 | In this video, I'm going to show you why it seems so easy to hold someone up against a wall. | 在这段视频中,我要告诉你为什么把一个人抱在墙上看起来那么容易. |
| 7 | In discussing this, we'll run into one of the deepest mysteries in physics, | 在讨论这个问题时,我们会遇到物理学中最深奥的谜题之一, |
| 8 | where the equations become undefined and even paradoxical in basic friction problems. | 在基本摩擦问题上,方程式变得不明确甚至自相矛盾。 |
| 9 | And then we'll see if I was able to successfully hold my son up. | 然后再看看我能不能成功地抱住我儿子 |
| 10 | But before we continue, I want to tell you about the sponsor for this video, Lien. | 但是在我们继续之前 我想告诉你这段视频的赞助商 Lien |
| 11 | They sent me their new Lien Pit Kit S1, | 他们送我新的连坑式S1 |
| 12 | and I've been using it all week to organize my house and print pictures. | 我整个星期都在用它来整理房子和打印照片 |
| 13 | The Pit Kit S1 uses a high-precision thermal print head, so it doesn't need ink or cartridges. | Pit Kit S1采用了高精度热印头,因此不需要墨水或弹匣. |
| 14 | All the color is inside the sticker paper itself. | 所有颜色都在贴纸本身内部. |
| 15 | The printer heats different layers in the paper to create the image, | 打印机在纸张中加热不同的层来创建图像, |
| 16 | then a tiny internal blade automatically cuts out the shape for you. | 然后一个小小的内部刀片 自动切断你的形状。 |
| 17 | And the setup took only about a minute. | 而设定只用了大约一分钟. |
| 18 | You just plug it in, load the paper, open the app, and then it's ready to go. | 你只要插上,装上纸,打开应用程序,然后它就可以走了. |
| 19 | And it also connects straight to your phone through the Lien app. | 而且它也通过Lien的应用程序直接连接到你的手机. |
| 20 | What's really cool is the AI smart cut and AI auto subject selection inside the app. | 真正酷的是软件内部的AI智能剪辑和AI自动题材选择. |
| 21 | You just upload a photo, and the AI instantly finds the main subject, | 你只要上传一张照片 AI立刻发现主角 |
| 22 | removes the background, and creates the perfect cut outline for you. | 删除背景,并为您创建完美的剪切大纲。 |
| 23 | Also, you can use the AI lab in the app to create different style cartoon versions | 另外,还可以使用应用程序中的AI实验室来创建不同的风格卡通版本. |
| 24 | of whatever pictures you take. | 无论你拍什么照片 |
| 25 | Here's a cartoon version of the same sticker I printed earlier. | 这里有一个卡通版 我之前印的同样的标签。 |
| 26 | This is so cool. | 这太酷了 |
| 27 | 我们用Lien Pit Kit S1为玩具罐做标签 | |
| 28 | backpacks, lunchboxes, chargers, and even in the pantry. | 背包 午餐盒 充电器 甚至在储藏室里 |
| 29 | My kids even drew their own characters, and with one tap the AI outlined them | 我的孩子甚至画了自己的角色, 用一个音响,AI描述他们 |
| 30 | and the printer cut them out automatically. | 和打印机自动剪除。 |
| 31 | You can also use it for DIY projects like custom water bottle stickers, | 也可以用于DIY项目,如定制的水瓶贴纸, |
| 32 | personalized gifts, scrapbooking, or decorating notebooks and laptops and computers. | 个人化礼品、剪贴簿或装饰笔记本、笔记本电脑和计算机。 |
| 33 | Also, Lien has completely upgraded the sticker adhesiveness this year, | 另外,Lien今年完全升级了粘贴剂 |
| 34 | so you don't have to worry about the stickers peeling off. | 所以你不必担心贴纸被剥掉 |
| 35 | They stick really well, actually. | 事实上,它们粘的很好。 |
| 36 | So if you're interested, now's a great time to check it out | 所以,如果你感兴趣, 现在是一个伟大的时间检查它 |
| 37 | because Lien is having a big Amazon Prime Day Sale with their lowest prices available. | 因为Lien的亚马逊日销量很大 价格最低 |
| 38 | So click the link in the description to view the product and learn more. | 因此点击描述中的链接来查看产品并学习更多. |
| 39 | Now let's get back to our experiment. | 现在,让我们回到我们的实验。 |
| 40 | Frictional force is equal to the friction coefficient times the normal force. | 滑动力等于摩擦系数乘以正常力. |
| 41 | The normal force is how hard the object is being pushed against the surface. | 正常力是物体被推向表面有多难. |
| 42 | So for an object just sitting on a horizontal table, | 所以对于一个正坐在水平台上的物体, |
| 43 | the normal force is equal to its weight because the object is pushing down with its weight. | 正常力等于其重量,因为物体正随重量推低。 |
| 44 | Now with these definitions in place, | 有了这些定义, |
| 45 | we can start to understand what happens when we hold a person up against a wall. | 我们可以开始理解当我们把一个人抱在墙上时会发生什么。 |
| 46 | For example, let's take this block. | 比如说,我们走这条街 |
| 47 | If I place it against the wall, it's going to slide straight down | 如果我把它贴在墙上, 它会直滑下来 |
| 48 | because there's no normal force pushing it against the wall. | 因为没有正常的力量把它推到墙上 |
| 49 | But if I push on the block, I can increase the frictional force | 但是,如果我推到街区, 我可以增加摩擦力 |
| 50 | by increasing the normal force until that frictional force | 增加正常力量直至摩擦力 |
| 51 | exactly equals the force of gravity pulling it down so it stays up. | 完全等于重力 把它拉下来 所以它保持上升。 |
| 52 | So with really high friction coefficients, | 摩擦系数很高 |
| 53 | this can actually give us a little bit of an advantage. | 这实际上可以给我们一点优势。 |
| 54 | If I solve for the required pushing force by dividing by the friction coefficient, | 如果我用摩擦系数除以所需推力 |
| 55 | you can see that if I have a friction coefficient below 1, | 你可以看到,如果我有一个摩擦系数低于1, |
| 56 | that means that I have to push it against the wall with more force than it weighs. | 这意味着我必须用比它重得多的力气把它推到墙上 |
| 57 | But if my surface has a super high friction coefficient above 1, | 但如果我的表面有超高摩擦系数超过1, |
| 58 | let's say it was 1.1 in this case, | 假设这案子是1.1 |
| 59 | then I only need to push it up against the wall with about 90% of its weight. | 那我只需要用90%的重量把它推到墙上 |
| 60 | But friction coefficients above 1 aren't that common. | 但1级以上的摩擦系数并不常见. |
| 61 | So let's see what the friction coefficient of a person against a wall is. | 让我们看看一个人对墙的摩擦系数是什么. |
| 62 | To measure this, I'm just going to measure the force it takes | 为了衡量这个,我只是要衡量它所需要的力量 |
| 63 | for me to start sliding on this piece of wall here. | 让我开始滑到墙上 |
| 64 | Okay, so I calculate depending on what's touching, | 好吧,所以我计算 取决于什么是触摸, |
| 65 | whether it's my skin or my pants or my shirt, | 不管是我的皮肤还是裤子还是衬衫 |
| 66 | I get a friction coefficient that ranges from 0.25 up to maybe 0.5. | 摩擦系数从0.25到0.5不等 |
| 67 | So that means to keep them up against the wall, | 也就是说要让他们靠在墙上 |
| 68 | I would have had to be pushing from anywhere from twice their body weight | 我不得不从任何地方推 从他们的体重的两倍 |
| 69 | to four times their body weight. | 4倍于他们的体重。 |
| 70 | But it wasn't that hard to hold them against the wall. | 但把他们挡在墙上并不难 |
| 71 | But why? | 为什么? |
| 72 | Well, look how I'm holding them up. | 好吧,看我怎么支撑他们。 |
| 73 | I'm pushing at about a 45 degree angle. | 我推进了大约45度角度。 |
| 74 | So some of my push is going to push them against the wall | 所以我的推力会把他们推到墙上 |
| 75 | and some is reducing their effective weight. | 并且有些人正在降低他们的有效体重。 |
| 76 | So if we combine them both, we get this equation. | 因此,如果我们把它们结合起来, 我们得到这个方程式。 |
| 77 | So now we can calculate the weight supported as a function of the push force required. | 因此,现在我们可以计算所支持的重量作为所需的推力的一个函数. |
| 78 | And something surprising happens. | 发生了一些意外 |
| 79 | The x-axis is how much they weigh | X轴是它们的重量 |
| 80 | and the y-axis is how hard I need to push against them at a 45 degree angle. | 和Y轴是多困难 我需要推向他们 45度角度。 |
| 81 | Once the friction coefficient gets above about 0.4, | 一旦摩擦系数超过0.4, |
| 82 | the force I need to apply is actually less than the person's weight. | 我需要施用的力量实际上比人的重量要小。 |
| 83 | In other words, I'm not really lifting them. | 换句话说,我并不是真的拿起它们。 |
| 84 | I'm using the wall to redirect my force into friction | 我用墙把力量引向摩擦 |
| 85 | and that friction is helping support them. | 摩擦有助于支撑他们 |
| 86 | That's why holding someone against a wall can feel much easier than simply picking them up. | 这就是为什么把一个人抱在墙上 感觉比捡起来容易得多 |
| 87 | So at first glance, friction seems simple. | 所以乍一看,摩擦似乎很简单。 |
| 88 | Push harder and friction increases. | 用力推,摩擦会增加 |
| 89 | Push less and it decreases. | 推少则减. |
| 90 | But hidden inside these seemingly simple laws | 但隐藏在这些看起来简单的法律 |
| 91 | is a paradox that's puzzled physicists for over a century. | 一个多世纪以来 物理学家们一直对此感到困惑 |
| 92 | For example, let's look at the friction at the tip of a pencil as it tips over. | 举个例子,让我们看看铅笔尖端的摩擦 当笔尖尖倾斜时。 |
| 93 | The solution to this problem looks like this | 这个问题的解决办法是这样的 |
| 94 | if we try to solve for the normal force of the tip of the pencil. | 如果我们试图解决铅笔尖端的正常力。 |
| 95 | Now this equation looks kind of scary, so let's just graph it instead. | 现在这个方程式看起来有点吓人,所以让我们用图表来代替它。 |
| 96 | I'll graph the normal force versus the angle of the pencil as it falls. | 我会在铅笔落下时 将正常的力量和铅笔的角度联系起来 |
| 97 | So if I do it on a normal tabletop with the friction coefficient of 0.4, | 如果我在普通的桌子上做 摩擦系数是0.4 |
| 98 | then we can see that the normal force increases as it falls and then decreases | 然后我们可以看到正常的力量随着下降而增加 然后减少 |
| 99 | and then the pencil tip lifts off the ground at some point and the normal force drops to 0. | 然后铅笔尖在某个时候从地面上升起,正常的力下降至0. |
| 100 | But now watch what happens. | 但现在看会发生什么。 |
| 101 | If I put the pencil on some very rough sandpaper | 如果我把铅笔 在一些非常粗糙的砂纸上 |
| 102 | with the friction coefficient really high like 1.8 or something, | 摩擦系数跟1.8一样高 |
| 103 | then in real life we can see the pencil still falls pretty normally. | 然后在现实生活中,我们可以看到铅笔仍然很正常地落下. |
| 104 | But now watch what happens in our equation. | 但是现在看我们方程式中会发生什么。 |
| 105 | You can see that the equation shoots off to infinity | 你可以看到,方程式 射向无限 |
| 106 | and also then suddenly comes back in the negative, | 突然间又出现了阴性 |
| 107 | implying that the table is pulling up on the pencil, which is impossible. | 暗示桌子在拉铅笔 这是不可能的 |
| 108 | These strange behaviors became known as the Paul Levy paradox, | 这些奇怪的行为被称为保罗·李维悖论, |
| 109 | and they reveal that friction may be far more mysterious than it first appears. | 他们揭示了摩擦可能比最初出现的要神秘得多. |
| 110 | Not only do the equations start predicting infinite and impossible values, | 不仅方程式开始预测 无限和不可能的数值, |
| 111 | there's an even more mysterious spot called the G-spot. | 还有一个更神秘的地方叫G点 |
| 112 | And no, in case you were wondering, | 没有,如果你想知道, |
| 113 | the name for this actually comes from a scientist named Christophe Genot, | 这个名字其实来自一个叫克里斯托弗·盖诺的科学家 |
| 114 | who first studied this special configuration here. | 他们首先研究了这个特殊的配置 |
| 115 | The G-spot is the point at which the governing equations of friction become undefined. | G-spot是支配摩擦的方程变成未定义的点. |
| 116 | We end up with a zero divided by a zero. | 我们最后以0除以0。 |
| 117 | At this point, the equation becomes undefined and can't predict what will happen next. | 此时,方程变得未定义,无法预测接下来会发生什么. |
| 118 | It's completely indeterminate at this point. | 此时完全不确定. |
| 119 | So during this transition or near it, | 因此,在这个过渡期间或附近, |
| 120 | friction can become unpredictable and highly sensitive to tiny disturbances. | 摩擦会变得不可预测,对微小的扰动高度敏感. |
| 121 | So we run into situations called dynamic jam and chatter, | 所以我们遇到了被称为动态干扰和聊天的情况, |
| 122 | like when chalk skips across a chalkboard when you're trying to write, | 就像当粉笔跳过粉笔板 当你试图写, |
| 123 | or when brakes squeal, or when machine tools chatter while cutting a metal. | 或当刹车刹车时,或当机器工具在切割金属时颤抖时。 |
| 124 | All of these situations happen in this regime where friction behaves highly unexpectedly. | 所有这些情况都发生在这一政权中,摩擦行为出乎意料。 |
| 125 | I always find it surprising when some of the simplest ideas in physics like friction | 物理学上最简单的想法 比如摩擦 我总是觉得很惊讶 |
| 126 | become unsolvable or even outright wrong under certain situations. | 在某些情况下无法解决甚至完全错误。 |
| 127 | This ultimately points to the idea that even our basic friction laws are incomplete. | 这最终表明,即使我们的基本摩擦定律也是不完整的. |
| 128 | So that's why in order to see if I can hold someone up bigger than me, | 这就是为什么,为了看看 如果我能抱一个人比我大, |
| 129 | I just have to try it myself. | 我只需要自己试试 |
| 130 | So let's see if I can hold up my oldest son against the wall, | 让我们看看我能不能把我长子抱在墙上 |
| 131 | using nothing but friction and a good angle. | 只能使用摩擦和好角度 |
| 132 | And thanks for watching another episode of The Action Lab. | 感谢观看另一集的动作实验室。 |
| 133 | I hope you enjoyed it. | 希望你喜欢 |
| 134 | If you have any questions, let me know in the comment section and I'll try to get to them. | 如果你有任何问题,告诉我 在评论部分 我会试着得到它们。 |
| 135 | And if you haven't subscribed to my channel yet, consider subscribing | 如果你还没有订阅 我的频道,考虑订阅 |
| 136 | and we'll see you next time. | 下次见 |
该视频共有字幕 136 条。解锁更多字幕为会员功能，请移动到 价格