The Mystery of Pendulums / Mr. Denjiro's Happy Energy!

DENJIRO: Today, I’m going to give you a quiz by performing an experiment with pendulums. Here, I have two balls of the same size suspended by string. Let me move one of the balls. As you can see, they repeat the same movement.
Now, here’s a quiz about collision. I’ve changed one of the balls to one that is smaller and lighter. If I strike the small ball against the big ball, will the movement be the same as before?
GIRL: Of course not.
DENJIRO: Let me give it a try. It’s moving differently from before. But if you look closely, it’s repeating the same pattern. Here’s another quiz. Now, what if I strike the big ball against the small ball? How will they move?
GIRL: I don’t know.
DENJIRO: Again, they move differently. But if you look closely, once again, they are repeating the same pattern. Even if you strike the small ball against the big ball or vice versa, it returns to the original position after two collisions. Let me explain what’s going on by taking a look at what happened when I struck the small ball against the big ball.
After the first time the small ball collides against the big ball, they both move away from each other. They then collide at the same point again. The speeds at which the balls move away from each other and when they collide again are the same. But the directions the balls move in are the opposite. Therefore, the pendulums returned to the original position after two collisions. The same happens when the big ball is struck is against the small ball. It returns to the original position after two collisions.
I hope energy will bring you all happiness. Our magic word is "Happy Energy!"

[@user-wu3qe8dt7t]

問題としてやった事があっても、実際に見てみるとやっぱり不思議

[@nicky_3ta]

解き方として運動量保存則を使うって分かるけど、実際にこんな綺麗に成り立つのは驚きです。

[@KagiJPN]

分からないですねw でクソ笑った

[@user-yw5dh9cw6u]

これ弾性衝突じゃなくても理論上は一定の周期になるよね

[@user-cq9qk2nx6l]

こういうの見て何でこうなるのか分からないときまだまだ自分の物理に対する理解は甘いんだなって実感する。もっと勉強しないとなー

[@user-cj5ys4vx6j]

制服にハッピーエネルギーって書いてあるの可愛い

[@toretorecc]

これ見ると。

[@syosyokun]

ぜんぜんなんでかわからなかった

[@minorusaito8265]

すばらしい、高校生のときとは違いますね。最近物理がおもしろい

[@user-pt5se5kk6t]

鉄球が止まる理由

[@user-zi7zp3op4b]

これって運動量保存の法則ってやつ？

[@user-ze8yc5qf7v]

小さい玉を止まっている大きな玉に衝突させたときに、小さい玉が反対側に動くのはなんでなの？

[@narisato5726]

物理って魔法みたいだな

[@Biot-Savart-law]

重さが違うから反作用の力が小さい方に多く加わって逆側に弾けてるって事かな？(違ってたら教えて下さい…)

[@user-rm1mx1di1m]

そこに剛性はあるんか？

[@ay-oha]

これ入試問題で出てそう

[@gip8054]

小さい球が大きい球に当たる時を考える

[@user-rd3np6cd9p]

なると思う！！(結果見る前)

[@karuchieable]

このチャンネルの動画色々見てみたが謎のまま終わったの初めて

[@tube7170]

大きい球を地球、小さい球を俺だとすると俺が地面に飛び降りてバウンド(ジャンプ)したらジャンプしている間だけ地球は若干俺に蹴り上げられているけれど俺が着地したら元に戻るってことか