Joining Lead Blocks Together / Mr. Denjiro's Happy Energy!
ฝัง
- เผยแพร่เมื่อ 30 ก.ค. 2020
- DENJIRO: Today, I’ll show you a mysterious phenomenon using these two blocks of metal. Now, how would you join these two blocks together?
BOY: Melt them together? Use glue?
DENJIRO: Let's find out. These two blocks are made of lead. Lead is a comparatively soft metal. We won't be using glue to join them together. Instead, we'll use this vise. We'll place the two blocks together and add pressure with the vise.
But this alone... does not make them stick together. Simply applying pressure won’t do. There's a little trick.
We'll place the blocks together at an angle and apply pressure using the vise. Then we'll put them in a straight line by pushing them down and making them rub against each other. Now, we'll take the blocks off the vise. Lo and behold...
BOY: They’re joined together!
DENJIRO: Interesting, isn't it? Why did these lead blocks stick to each other? Lead is a soft metal, so when the two blocks get pressed together, their surface gets slightly deformed, and the area of contact is increased. But this alone will not join the two blocks together. The surface of lead is covered with an oxide film, which forms due to a chemical reaction with oxygen. This film prevents the two blocks from sticking together.
When the two surfaces rub against one another under pressure, the oxide film breaks. Now, the two blocks can be joined together.
Let's test how strong the bond is by lifting a weight. We have here 15 two-liter bottles of water, which weigh about 30 kg in total. Let's try lifting this.
BOY: Amazing! The lead blocks lifted the bottles!
DENJIRO: As you can see, the two lead blocks are firmly joined together. But if you hit one of the blocks from the side with a hammer...
They break apart very easily. Their bond is strong against a vertical pulling force, but weak against force from the side.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!”
「これ横から叩いたら外れるんじゃない？」という疑問を間髪入れずに解消してくれる先生に惚れそう
でんじろう先生って10年前から見た目が変わらないけどどんな科学を使ってるんだろう？
これ、実はでんじろう先生がとてつもなく大きな力でハンマーを振っているから剥がれるんだよね……
助手がイケメンすぎて草
あーなるほど、ネジがカジッたときも同じ現象が起きとるのかー。
万力にしめる方向書いてあるの可愛い
真空中でやればさらに強く接着出来るんじゃ・・・
で「人間関係も縦の繋がりは強くても横は簡単に崩れてしまいます」
摩擦熱で表面が溶けてくっついたのかと...
ハンマー振る瞬間だけ界王拳を使ってることぐらいはわかるよ流石に
地上ではむき出しの金属にはすぐ酸化膜が生成されますが、宇宙では表面の酸化が起こりづらく、金属などはすぐくっついて動かなくなってしまうので
衛星の設計時などは気を付けないといけないと大学で習いました。
この実験は最初地味かと思いましたが、びっくりしました。
酸化鉛の被膜ができるからそのままだと接着しないのか…
縦方向にこれだけ強いだけで驚きだわ
10年ほど前は別の方法で鉛の接着実験してたのを覚えてる。
大昔に 名探偵コナンの理科本で見ました
I just have found another good channel. Keep up your great work, Denjro-sensei.
Great show! I hope you get some slow-mo cameras to do some slow mo shots like him hitting that thing with a hammer!
このまま、でんじろう先生がぶら下がったら面白かった
コロコロコミックみたいなページ数の多い本を一ページづつ重ねていくと、すごいガッチガチになる動画だったかテレビ番組だったかを思い出した