ADM-201 dump PMP dumps pdf SSCP exam materials CBAP exam sample questions

扫帚谜题(3) – 译学馆
未登录,请登录后再发表信息
最新评论 (0)
播放视频

扫帚谜题(3)

The Broom Riddle (Solution) ft. Kurt Hugo Schneider part 3/3


[MUSIC PLAYING] Hey,
我是戴安娜
I’m Diana.
你现在收看的是物理女孩节目 这是
You’re watching Physics Girl,and this is video number 3
‘’考问我朋友们的那些谜语‘’系列的第三期
in the series of riddles that I’m asking to my friend,
这位嘉宾Kurt
Kurt Hugo Schneider, who
他正好是‘’油管‘’上一位非常著名的音乐播客
also happens to be areally big music YouTuber.
上期节目我们留下了一个关于扫帚的谜语难题
We left off in the lastvideo with the Broom Riddle.
我们再重复一下那道题
So here’s the setupfor that again. OK,
我现在要把这把扫把平衡的放在我的手指尖
so I’m going to balance this bloom on my fingers
所以我的手指现在在它的重心位置
so that my finger is underneaththe center of gravity.
对于一把普通的扫帚来说
For a situation like anormal broom on earth,
你可以选择放在它本身的中心或是它的重心
you could either use centerof mass or center of gravity
好了
for this riddle. OK,
我现在假设我们要
so I’m going topretend that we’re going
把扫帚从这个位置
to cut the broom right here.
就是平衡点的位置切断
Right where you balance it.
平衡点在这
Right where I balance it.

OK.
现在你有了两部分
So now you have two pieces
一个是扫帚的手把部分
of this broom, this handle part
一个是扫地的部分
and then the sweepy part.
好的
OK.
这两边哪部分是更重的
Which of thesesides is heavier,
还是它们俩一样重?
or are they the same weight? Well,
如果你想在我们接着往下做之前猜一下 请暂停
pause if you want to guess before we continue
这边肯定更重
This side has to be heavier
因为这边切出去了
because that side goes out
这么长一部分
so much further.
我的意思是 如果我们想象有一把扫帚
I mean, if we just imagine a”broom,” which is basically
它有一个很长的棍把 这端还有非常非常重的扫把
a long stick with oneenormously massively heavyweight
那么它的平衡点应该
on this end, then thebalancing point would–
总处于这个位置 对
this side is always going to — yeah,
平衡点应该非常靠近这里
the balancing point would be very close to here.
这一段将会更重 但是这一段
This side is going to bemuch heavier, but this side–
它仍然能平衡 因为在那端的一段非常远
it still balances because thatside’s so far over there, so
它们的转矩 或者随便你怎么说 它们是相等的
the torques, or whateveryou call it, balance out.
这一段就是更重的
This side has got to be heavier.
厉害
Amazing.
你太棒了
You killed that, awesome.
你的说理方式是我最喜欢的一种
Your reasoning was my favoritetype of reasoning, which
就是把这个谜题
is taking the riddle and you’re like, let’s
设定它的极限情况
take it to the extreme, which is like if this
就像假设这段是非常非常重 很明显
is super, super heavy, which obviously,
这一段就会比扫把其它部分更重
this part is heavier thanthe rest of the broom.
这个不是已知条件 不过你想到了
That wasn’t a given, but if you’ve ever felt a broom,
你平衡这把扫把的关键就是力矩
what you’re balancing is the torques.
你在平衡两段的力距
So what you’re balancing is the torques,
因为这把扫帚的这段这么长
and because the broom goes so far over this way,
你有了一条长轴
you get a long distance,
和扫帚更轻的这部分
and then a little bit of mass,
然后是这边更重的部分和一条短轴
and then big mass andshort distance over here.
但当你进行平衡力距计算时 也就是用距离乘以重量
But when you’re balancing torques, which is distance times force,
在这个等式中 你并没有考虑重力
you’re not putting those gravitational forces in those equations
对扫把两端的影响 而是
at the ends of thebroom, but rather, you
你把它图解成重力处在
diagram it so thatthe forces that
两边的中点 当然了
are acting on the center of mass of each of the sides. Still,
左边的距离更长
the distanceon the left is longer,
那么这一部分重量就肯定更少
so that mass has to be less.
但是还有一种情况就是
But there is asituation in which
我看看我能不能说对
the — let me see if I can get this right —
更长的那部分
the longer
也许会更重
side of that cutcan be more massive.
那么对于这种情况你有什么解法
So think if you can come up with a situation like that.
再具体点说 如果你得到的杆子
So more specifically, if you’ve got a rod
是不同分布重量的 你能不能
with some distribution of mass, can you make it
在更重的这部分的中间
so that when you balance your finger
找到平衡点
on the center of mass
然后再从那里切断 这个更长的部分实际上
and then cut it there, thislonger side is actually
是不是更重?
more massive?
如果你有什么想法 就在评论里写出来吧
If you have a guess,leave it in the comments.
现在我们来进行下一个谜题
Moving on to the next riddle.
你已经回答了很多的谜题了
You’ve already answered plenty of riddles,
接下来这个你可能需要用到纸和笔
so you might even want pen and paper for this. OK,
纸和笔
pen and paper.
有了
Got it.

OK.
我给你两个2 两个数字2
So I give you two2s, two number 2s.

OK.
一个2 和一个2
A 2 and a 2.
一个2 两个2
A 2 and a 2.
好了
All right.
你可以用所有普通的数学符号对它们进行
You can do anything withthem with pretty common math
运算
symbols.
比如说 2的2次方就是4
So for example, 2to the 2 would be 4.
2加2是4
2 plus 2 would be 4.
2乘以2的开平方根就是
2 times square rootof 2 would be–
懂了
Got it.
就是2的开根号二
So 2 root 2.
你甚至可以用2.2这个数
So you could even do like 2.2.
懂了
Got it.
那我也可以用22
So I can also do 22.
我可以连接它们
I can concatenate them.
你可以用22
You can do 22.

OK.
现在我想让你试试用他们算出5
So I want you to tryand make the number 5.

Got it.
用两个2
Using two 2s.
只能用两个2
Just two 2s.

Just two 2s.

All right.
这是最简单的
The simplest.
这些是日常会用到的数学符号
These are the everydaymathematical symbols
允许你使用这些
you’re allowed to use.

OK.
如果我在镜子里看到一个2
Totally cheating if I look at one
然后说这是5
of the 2s in the mirror
这属于作弊吗?
and call it a 5, right? Yes,
对 这是作弊
that is cheating. OK,
好吧 就是确认一下
just making sure. Yeah,
那你开始吧
there you are.
我算算
Making sure.
我把2放在上面然后
So I’m going to put a 2 on top,
开个平方根
and then take the square root,
然后再开平方根 再继续开根
and then take the square root, and then take the square root.
然后我在这里点点点
And then I’m going to add a dot, dot,
不停的开根
dot, dot, dot, so
也就是2的无限开平方根
an infinite square root of 2.
因为这样就接近于1了
Because that approaches 1.
好吧
Uh-huh.
然后再除以0.2 就得到了5
And then divide by 0.2 for 5.
所以这就是不停的
So this is really dot, dot, dot.
接近于无限运算的方式
So this is sort of just aninfinite operation here.
你这是在绕开我的规则哦
You got around my rule. Yeah,
不停的加上点点点可不在给出的规则里面
but the dot, dot,dot is not listed here,
这可不行 Kurt
and that iscertainly something– Kurt,
这是违反规则的
it’s against the rules.
但是这种跳出笼子的思考方式
But that kind of out-of-the-boxthinking should not be
也不应该被禁止
squashed.
应该得到鼓励 所以我要为你的解法鼓掌
It should be encouraged, and soI applaud your solution, Kurt.
不过这里有一个更简单的方法
It’s just thereis a simpler way.
不耍小聪明了
There’s no trick, OK.
我真心想把这题解出来
I genuinely wantto figure it out.
1除以0.2得到5,5的平方再开根就可以得到5
Square root of 1 over0.2 squared is 5. OK,
那么我只需要把这个1去掉
I just need toget rid of the 1.
0.2的负2次方再开根号
Square root of 0.2to the negative 2.
我可以用负数吗?
Can I use negative?
可以用负2吗?
Can I use negative 2?
这是允许的 对吧?
That’s allowed, right?
你可以用负2
You can use negative 2. OK,
好 这是解法吧?
is that the solution?
就是这样
That’s it.
是这样?
That’s it?
对对
Yes.
就是这样
That’s it.
太好了
Sweet.

Yay.
太棒了
That was amazing.
没有比这更简单的了
There’s nothingsimpler than that.
这很难啊
That was a tricky one.
不得不说 这道题真的有点难
I have to say, thatwas tricky right there.
数学专业的在这
Math major right here.
我觉得你不应该只玩音乐
I feel like you shouldn’tbe doing only music.
真的 要用上你的数学学位啊
Really using that math degree.
这是我近十年来第一次用上数学
First time I’ve used my mathdegree in nearly 10 years. OK,
好啦 我现在很有热情啦
now I’m pumped.
这道题真的让我信心满满
This one pumped me up.
非常好
That was really good.
Kurt 想破解更多的谜题 所以我给了他一个福利题
kurt wanted more riddles, so I gave him a bonus
现在我开始想这道题了
Now I’m thinkingabout this one, though.
我知道你们当中肯定想知道
I know some of youcan’t go on with life
我到底给了科特什么题目
without knowing whatriddle I gave Kurt, so here
这就是最后一道奖励题
is the final bonus riddle.
我明天会把答案放在说明里面
I’ll put the answer inthe description tomorrow.
科特有25分钟没有理我 因为我给了他
I lost Kurt for about 25minutes because I gave him
另外一道题目
another riddle.
我确实算出来了
I did get it.
你是算出来了
You did get it.
但是这题很明显有一些更简单的方法
But there’s clearlysome clever rotational,
或者说有更直接的方法做这题
or there’s some veryintuitive way of seeing this.
我知道你接下来的晚上
I feel like I know what you’re going to do
准备干嘛了
with the rest of your evening.
我给了你一道数学题 你就这样 不
I give you a mathproblem, you’re like, no. Like,
等一等
hold on. Like,
等几分钟
just a minute.
我就像这样:科特 我们可以之后再做吗
I’m like, Kurt,can we do it after.
你就说 再等一等
You’re like, just a minute.
这个很有趣啊
This was amazing.
谢谢
Thank you.
哦 不 谢谢你
Oh no, thank you.
非常感谢你
Thank you so much.
这个确实很有趣
This was so much fun.
这对我来说很有趣
This was so much fun for me.
感谢大家观看
Thank you guys for watching.
这位是很有趣的嘉宾
It was a fun guest.
学习物理愉快哦!
And happy physicsing.

Yeah.
音乐
[MUSIC PLAYING]

发表评论

译制信息
视频概述

关于扫帚重心的判断,还有一个数字题。挺有意思的。

听录译者

收集自网络

翻译译者

果子

审核员

审核员H

视频来源

https://www.youtube.com/watch?v=9EkUvuHBm38

相关推荐