[요약리뷰] 언더스탠딩 - 장난감으로 보는 물리학, 김범준 교수

 

### 한글 요약:

성균관대학교 물리학과 김범준 교수는 장난감을 통해 물리학의 원리를 쉽게 설명합니다. 그는 장난감을 이용해 수업을 하며, 무게 중심, 공명, 현수선 등 다양한 물리학 개념을 소개합니다. 예를 들어, 무게 중심을 잡는 새 모양 장난감, 외줄 타기의 안정성을 위한 긴 장대 사용, 우산을 이용한 마찰력 실험, 팽이를 통해 각운동량을 설명하는 등의 예시를 통해 물리학의 기본 원리를 설명합니다. 또한, 베르누이 원리를 이용해 공이 공중에 떠 있는 현상, 갈톤 보드를 통해 정규 분포를 시각적으로 설명하는 등 다양한 실험과 예제를 통해 물리학의 원리를 쉽게 이해할 수 있게 도와줍니다. 마지막으로, 물리학을 이해하는 것이 중요하며, 학생들에게 이러한 장난감과 실험을 통해 물리학을 재미있고 쉽게 가르치는 것이 목표라고 말합니다.

### English Summary:

Professor Kim Beom-jun from Sungkyunkwan University's Department of Physics explains the principles of physics using toys. He uses toys in his classes to illustrate various physics concepts such as center of mass, resonance, and catenary curves. Examples include a toy bird that balances on its beak to explain center of mass, using a long pole for stability in tightrope walking, and a friction experiment with an umbrella. He also demonstrates angular momentum with spinning tops, the Bernoulli principle with a floating ball, and visualizes normal distribution with a Galton board. Through these examples and experiments, he makes the fundamental principles of physics easy to understand and enjoyable. He emphasizes the importance of understanding physics and aims to teach students in an engaging and accessible way through these toys and experiments.

 

 

장난감을 보면 물리학이 보인다고요? (성균관대 물리학과 김범준 교수) - YouTube
https://www.youtube.com/watch?v=QRjHa2xQSHU

Transcript:
(00:00) 세상의 모든 지식 언더스탠딩네 자 금요일 저녁이라서 오늘도 과학 이야기 준비했는데 저도 이제 물약에 대해서 별로 모르다가 물약 조금씩 조금씩 배워보는데 아 너무 재밌거든요 오늘은 물리학 장난감 물리학으로 만든 장난감 이야기 물리학도 재밌는데 장난감가 오늘은 고네 아 물리 장난감 게 원리를 이용해서 이렇게 장난 장난감을 만 애들 장난감도 요런 걸 줘야 애가 똑똑해지고 좋은학교가 륭한 람 그렇지 그렇지 똑같은 걸로도 어떻게 이렇게 할 수 있나 오늘 이거 아빠들이 잘 보셔야 될 것 같습니다 힘들어 힘들어 힘들어 성균과대학교 물리학과의 김범준 교수님이 오늘 장난감도 엄청 많이 가지셨어요 오늘 아주 재밌는 물 이야기 들려주 습니다 지금 교수님이 되 지금세요 선 준비중입니다 이제 다
(01:06) 올려습니다네 하고 있습니다네 모셔볼게요네 김범준께서 오시오 예 안녕하세요 송원대 물리학과에서 일하는 김범준입니다 김범준 신 덕분에네 어 다른 과은 모르겠지만 물리학과는 무조건 성균관대가 넘버원이네 원래 다 알고 있습니다 스카이의는 성균관의 다 예 당연하죠 예이야 아니 책도 쓰셨어요 최근에 저 앞에 보인 물리 장난감이라고 하는요 책도 진짜 장난감 물리학을 이용한 장난감 책입니까 책은 어 제가 그 대학교에서 학생들을 가르칠 때 그 장난감을 이용을 해서 보여 주면서 설명하는 방식을 좋아하는데요지 수업시간에도 예 그래서 수업 시간에 사용하려고이 장난감들 꽤 오래 모았어요 그래서 이걸 모아서 수업에도 활용했었는데 그 장난감을 소개하는 책을 요번에 낸 거죠 아 아 알겠습니다 뭐 하나씩 배워 보죠 뭐 무슨 무슨 장난감 있을까요 뭐부터까요 아 일단 좀 간단한 거부터 할게요 예 이게 사실
(02:11) 그 보통은 새 모양 장난감으로 파는데요 사실 우리가 쉽게 만들 수 있는 아주 간단한 장난감입니다 손 끝에 올려놓고 그냥 평형을 잘 잡는 거네 손 끝에 올려 놓으면 얘가 이렇게 평형을 잡아서 사람들이 이걸 보면 좀 신기해 하거든요 근데 사실 뭐 별게 아니라는 걸 말씀드리고 싶어요 예 이게 사실 이걸 제 PPT 화면을 보시면은네이 새 모양이 그 여기 보면 여기 렇게 점 c 있잖아요 여기가 새 불이라고 생각하시면 돼요 그다음에 새 양쪽 날개가 a 아고 B 이렇게 두 막대로 표시했다고 생각하시면 되는데요 a 아고 B 두 막대는이 a b 또 모아서 a b 의 무게 중심을 생각하면 그냥 가운데 a 아고 B 연결하는 선의 중간점 사실 옆으로 옆으로 직선을었을 때 그래 사실 그래서이 새 첫 번째 그림을 간단하게 줄이면 사실은
(03:14) 이겁니다 응 아 그렇죠네 그 a 아고 B 무게 중심을 m이라는 곳에다가 두면 그러면 그냥 C 아는 점에 그이를 매단을 손으로 잡고 있는 상황이랑 똑같죠 이해되시나요 아초 무슨 말이 모르겠는데 잠깐 이게 지금 새 손에 올려놓고 평형을 잡는 장난감을 보여 주신 거잖아요네 이걸 일단 간단하게 하는 거예요 그래서이 새 요쪽 날개 있잖아요이 새의 오른쪽 우리가 보기에 새의 오른쪽 날개 전체를 a 아는 곳에 새 날개 전체의 질량이 모여 있다라고 놓으면이 전반이 이쪽 오른쪽 예 날개의 무게 중심을 a 할 수 있고요 그렇죠 우리가 보기엔 왼쪽 날개 아 그렇죠 우리가 보기에는 왼쪽 날개 맞습니다 그다음에 우리가 보기의 오른쪽 날개의 무게 중심을 b라고 하면이 새는 사실은이 첫 번째 그림처럼 우리가 간단하게 그림을 그릴 수 있잖아요음 그래서 예
(04:18) 한편 그다음에는 또 a 아고 b의 무게 중심을 생각하는 거예요 가운데가 가운 그 가운데 그러면 a 아고 B 대신에 그냥 제가 m이라고 적은음 질량 하나를 a 지우고 그렇게 할 수 있겠죠 예 그럼 바로요 상황이 됩니다 그 사실 새가 무게 중심을 잡는 거는 그냥 우리가 C 점을 손가락으로 꼭 움켜지고 줄을 드리워서을 매단 거랑 똑같은 상황이거든요 그럼 얘가 당연히 중심을 잡을 수밖에 없잖아요 아 그래서 그냥 그냥 매단 뭘 뭘 뭘 매단다면 이렇게 들고 있는거나 상황이 똑같다는 겁니다 아 똑같다 그래서 항상 대충 잡아도 항상 중심 예 그래서 얘는 결코 예 그래서 아주 간단합니다 아 그런데 이제 금방 눈치 채실 수 있는게 아까 그 그림에서 예 a 아고 B 무게 중심을 하나로 합한 m 있잖아요 그게 위에 있으면 어떻게 될까요 예 손에 잡고 있는 것보다 위에 그럼 얘가 중심을 못 잡잖아 그래서 항상이 장난감을 보실 때
(05:21) 유심히 볼게요 잠자리 호은 새의 부리와 날개를 비교하면 날끝이 약 살짝 밑 미티어 돼 이것보다 아래에 있어야 돼 아 그래야 위에서 밑을 잡고 있는 것처럼 보이니까 그러면 그 장난감에서 그 길쭉한 반대쪽 길쭉한면 있잖아요 그거는 아무 그냥 상관이 없는 거네요 그거는 길어도 되고 짧아도 되고 상관 없습니까 어 그게 그렇죠 예 예 어 그건 좀 헷갈리네요 그래서 외줄 타기 할 때 서커스에서 그 외줄 타는 분이 길다란 장대 들고 와서 이거 외줄 타잖아요 저 장대는 왜 들고 다 요즘 혼자 타 근데 그게 말씀하신 대로 그대 양끝이 양쪽의 끝이 가운데로 모이니까 어 그 그렇게 일부러 중심 잡는 모양이네요 어 많 아주 중요한 포인트인데요 그분들이 사용하는 막대가 그 꼭한 막대가 아니라 휘는 막대하면 휘 밑으로 돼 있구나 아니 사실 그렇진 않아요 그런데 만약에 그런 막대하면 뭐 아무도 누구 연습도 안 해도 누구나 줄 위에 올라가도 안 넘어갑니다 아 그런데 그분들은 사실
(06:25) 그거는 그 정도는 아니에요 그분들이 사용하는 막대가 그런데 막대를 긴 걸 휘고 일부러 긴 거하시는 거 같은데요 그것도 도움이 되죠 휘지 않아도 도움이 되거든요 왜냐하면 이게 엄청나게 무거운게 길게 있으면은 이게 돌아가려고 하는 그걸 관성 모멘트 하는데 관성 모멘트가 커져서 잘 안 돌아가거든요 그래서 무거운 막대를 굉장히 긴 걸 잡고 줄 위에 올라서면 중심 잡기가 쉬워요 아무것도 안 들고 있으면 아주 위험하고 그래서 우리가 이게 중심잡기 게임할 때도 적으로 팔 걸리나 보적 예 양쪽 끝에 그럼이 팔을 벌렸을 때도 양 이렇게 하고 양쪽에 무거운 걸 들고 있으면 더 잘 되겠 훨씬 더 도움 듭니다 아 그래 내가 그래서 새는 양쪽에 날개로 난다 그게 뭐 좌우 그 진보 모수의 문제가 아니라 그냥 중심 잡으려고 양쪽에 날개로 나는 거예요 자꾸 그런데가 갖다 붙이지 맙시다 아 팔을 벌려서 아 아까 방금 질문하신 것 중에 이쪽 방향 이쪽 방향이 꽤 중요한데요 여기
(07:30) 음 리가 있고 날개가 리보다 앞에 있어야 돼요 앞에 있어야 돼 예 그래야지만 꼬리는 뒤쪽에 있으니까 그 이쪽 방향으로도 중심을 잡으려면이 날개가 또 앞으로 있어 그래 잠자리 보면 앞으로 앞으로 돼 있어 그래 실제로 그래서 사실 신기해는 보이는데 이해하고 나면은 너무 당연한 그래서 이걸 만약에 이렇게 하면은 당연히 중심을 못 잡죠 이렇게 하면 자리도 보다 얘가 위에 있으니까 그러니까 위에 위에 달려 있는 셈미 줄을 밑으로 이렇게 끌어올려 네 당연히 그 그데 그 자리에 있을 수가 없죠 이게 무게 중심에 관계된 건데요 무게 중심을 갖고 또 하나 쉽게 제가 설명드릴게 우산 예 우산입니다네 제가이 우산의 무게 중심을 눈을 감고 찾을 수 있습니다 그건 무슨 약간 마술사들이 하는 거 아닙니까 마술사들 눈을 감았어요 그다음에 이렇게 손가락을 조금씩 움직여요 예 그러면 항상 무게 중심으로부터 멀리 있는 손가락이 움직입니다 무게 중심이 왼쪽이 왼쪽 손가락이 움직이죠 아 그러다가 손가락이
(08:36) 만나잖아요 거기 중심이요 예 어 아니 잠깐 잠깐 잠깐 잠깐 잠깐 잠깐 잠깐 아니 내가 그냥 손을 이서 이렇게 울렸는데 했는데 예 한번 한번 한번 해 보세요 한번 해 보세요 무게 중심을 향해서 손이 저절로 가는 거예요 그러니까 자 이렇게 되어 있으면네 이게 내가 이쪽이 손이이 손이 움직이죠 무게 중심쪽으로 그 가운데가 뭐지가 무게 중심일테니까 근데 무게 중심이 가까워지면 어 얘는 얘는 얘 그대로가 움직여 이선은 무게 중심이 이미 가까워졌고 먼 쪽이 저의 왼쪽 여러분 시에 오른쪽이 되니까 얘가 저절로 움직인다는 거지음 아 지금 일부러 그렇게 하는 거 아니야 이렇게 이쪽으로 이렇게 했다가 이렇게 했다가 그거 아니야 국민들의 마음도 국민들의 마음도 중심에서 멀어진 쪽 쪽으로 로 움직이는 겁니다 그러니까 진보 보수의 문제가 아니라 너무 극단으로 가는 거가 싫은 거예요 같은 거야 해보세요 아 그래이 이렇게 그러면 그냥 이렇게만
(09:41) 해도네 한쪽만 움직이 한쪽만 움직이네요 그렇지 오야 이건 왜 그렇습니까 이거 왜 렵 우리가 마찰력이 하잖아요 마찰력 뭐가 있으면은 우리가 뭘 밀려고 하면 안 움직이려고 하는 힘 그게 이게 무거우면 무거울수록 마찰력이 더 크거든요 그렇겠죠 그렇죠 누가 누르면은 더 마찰력 력 지겠죠 무게 중심에가 있으면 많이 누리는구나 그래서 무게 중심으로부터 먼 쪽이 손가락에 작용하는 마찰력이 작아요 근데 이게 옆으로 그냥 평평하게 있는데 무게 중심으로 더 힘이 많이 눌려요 양쪽에 힘이이 가운데로 모인다고 볼 수 있습니까 그래서 그 무게 중심으로부터 더 먼쪽에 있는 쪽이 이 힘이 작고 가까운 쪽이 힘이 커요 예 그러면 마찰력이 먼 쪽이 작죠 그래 항상 눈을 감고 손가락을 움직이면 보면 무게 중심에서 먼쪽 손가락이 움직여요 아 힘이 누르는 힘이 약한 데가 그냥 흘러가는 거고 그쪽이 마찰력이 작아서이야 항상
(10:46) 중도는 강하다 와 그래서 중도가 표를 다 모으는 거야 눌러주는 힘이 있거든요 물량 얘기해 또 굉장히 놀라운 의미들을 찾 중도로 접근할수록 르는 미가 다 아 폭발력이 있네 중도가 아 그런 거구나 그래서 그래 저는 이게 옆으로 돼 있으면 그래도 누르는 힘은 다 같을 거라고 생각했는데니다 긴게 있으니까 그런 거군요 아까 전에 막대기가 양쪽지 가운데로 모이듯이 예 제가 알기로도 트럭에 짐을 많이 실은 다음에 그분들이 그 그 검사하는데 있잖아요 그때 그 트럭 위에 올려 있는 짐의 분포를 잘 바꾸면 음 그 짐을 좀 과해도 아 단속되지 않는 방법이 있다고 뜻 들었어요 그것도 비슷한 거죠 그것도 예 위치마다 다르니까음 그 아 무게 중심 갖고 하나 또 얘기할까요 예 이거는 예 어 신기하네요이 책의 무게 중심을 잡는 방법입니다 물리 장난감 책 교수님
(11:50) 쓰신 책 아니 뭐 제 책이 아니어도 다른 책들 무게 중심을 찾을 수 있는데요 아이디어 간단한데요 제가이 한쪽 귀퉁이를 잡고 얘를 늘어뜨려 그럼 내가 왔다 갔다 다가 이렇게 어떤 모양을 이루아 그때 손으로부터 제가 수직선을 긋는 거예요음 그러면이 수직선 위 어딘가에 무게 중심이 있어야죠 그래야 돼요 그래 만약에 만약에 수직선이 요렇게 돼 있었다 만약에 얘가 무게 중심이 여기서 수직선이 아니라 이렇게 돼 있었다 옆으로 그럼 얘가 이쪽으로 움직여야 되잖아요 그렇죠 그렇죠 그렇죠 그렇 여길 잡고 가만히 그냥 늘어 세우면 손가락으로부터이 지면을 향해 수직선을 그 위 그 여기다 선을 하나다고 생각하시고 그다음엔 그냥 다른 통이 잡고 또 똑같이요 그럼 또 수선 선 그럼 두 선이 만 거기가 무게 중중 그래서 해보시면 재밌는데 그렇게 무게 중심을 찾은 다음에 거기다 손가락을 잡고 요렇게 하면은 제가 중심을 잡집 돌 옛날에 어렸을 때 저 무게 중심
(12:54) 자가지고 돌리는 거 그 연습 많이 했는데 저는 잘 못해 그제가 있는 친구 그 반에 친구 중에 진짜 잘하는 애 있었어요 예 그 옛날에 그 많이들 했었는데 딱 자고 딱 얼면 딱 계 농구 잘 돌리는 친구들도 있었고 그죠 이것도 간단한 방법으로이 좀 널 널찍한 뭐 노트 같은 그런 것들의 무게 중심을 잡는 찾는 좀 쉬운 방법이 있습니다 물리학은 무게 중심을 찾는게 중요한 중요한 일입니까 모든 것에 중요하죠음 그니까 요런 책을 주면서 어 책 표면에 손을 대지 않고음 음 어 무게 중심을 찾아봐라 이렇게 잘 만드는 거니까음 그러면 그렇죠음 참기름 같은 거 갖고 와서 부어 참기름 이렇게 한 부어보고 어 됐지 그다음 여기 딱 이렇게 잡고 또 참기름 한번 이렇게 띡 부어보고 참기름 줄기와 참기름 줄기가 만나는 응 거기가 무게 중심 뭐 꼭 참기름을 해야 됩니까 선을 그어도 되는데 그게 선분을 정확하게 아래로 선분을으려면 그게 참기름이 딱 좋아요 이게 물이면
(13:57) 또이 막 옆으로 흐르기도 하고 케첩이 또 잘 안 내려와서 확하게 떨어지 떨어지고 싶어서네 그냥 참기름으로 해 그냥네네 알겠습니다 어 무게 중심 얘기좀 무게 중심 이야기 무게 중심을 가지고 야 이거 응용이 많이 가능하네요음음 알겠습니다 알겠습니다 또 그다음에 이게 혹시 뭔지 아세요 아 머리 이렇게 시원하게 하는 두피 마사지 어우 시원하네요네 저도 처음에 이거 그냥 그것도 물리 뭐가 있어 깊이 마사지 하려고 샀는데 이게 그 재밌는 물약의 현상을 설명할 수 있는 장난감이 되더라고요 한번 유심히 보세요 여기 보면 긴 철사가 있고 짧은 철사가 있잖아요 제가 긴 철사마 잡아당겼다 놓으면 나중에 어떤 철사가 떨리는지 보세요 전체가 떨리는데요 긴 것만 떨리죠 긴 것만 떨리네 주로 예 한편 어 짧은 거를 갔다가 놓으면 짧은 거어 짧은 거 그 왜 그래요 그 왜왜 밑에가 밑에가 짧은 건을 이렇게
(15:03) 연결해주는 거 아니야 짧끼리 연결해 짧 짧은니까 아니에요 여기가 같이 묶여 있습니다 예 어 지금 다시 봐도 신기하네요 예 이건 물약에서 왜 왜 왜 그 공명이라는 현상이 있거든요 근데 사실 공명은 여러분도 많이 느껴요 얘를 제가 느낀 것 중에 하나가 집에서음 그 오디오 굉장히 크게 음악을 들으면 가끔 음악이 뭐 드럼 소리처럼 저음이 울릴 때 그 집에 유리창이 떨리는 거하는 거죠데 그게 유리창은 그 뭐 드럼 소리라든지 낮은 름이 날 때만 떨리거든 높은 음일 때 안 떨리고 그게 이게 사실 그 이거랑 비슷해요 그래서 예를 들어 제가 얘를 이렇게 움직였으면이 긴 철사가 움직이면서이 전체에 진동을 전달하자아요 예를 들어 방금 설명드린 음악에서 내가 드럼 소리 같은 거예요 그런데 드럼 소리가 가지고 있는 소리의 진도 와 정확히 같은 진동수로 진동을 하는 물체가 집에 있으면 그 물체가 함께 떨려
(16:06) 그게 유리가 유리장인 거죠 거기서 그래서 똑같은 진동수를 얘가 그 움직이면 얘가 떨리는 진동수와 같은 진동수를 갖고 있는 철사는 더 크게 진동해요 아니 그런 거 아니 이게 진동이 가면 떨리게 하는 건 알겠는데 예를 들면 여기 진동의 파장이 있어요 그 얘가 좀 약해 약한 애가 더 떨리는 거 아닙니까 그게 같아야지 잘 떨 같아 떨려요 같아요 같으면 왜 떨려요 아 그게 이제 그 몇 가지 얘기를 할 수 있는데요 이게 아 아주 간단한 예 그 일상의 예를 얘기해 볼게요 놀이터에 가서 아이가 애를 타요를 타 애를 탈 때 우리가 밀아 근데 제가 뭐 밀 뭐 밀지 않아도 네가 그냥 갔다가 나한테 오는게 1초에 한번 온다고 생각해 보세요 1초에 한번 그러면 제가 1초에 한번 밀어야지 예 1초가 아니라 0.
(17:02) 8초 만에 밀면은 당연히 힘들죠 힘들죠 오는 걸 밀 수도 있고 그러면 진폭이 줄어들죠 그런데 1초에 한 번씩 규칙적으로 밀면 어떤가요 그럼 잘 가요 밀고 조금 있다가 또 밀고 그러면 제가 살살 밀어도 계속 반복을 하면 그네의 진폭이 커지죠 그예 그러니까 여기서도 진동수가 두 개가 있는 거예요 하나는 제가 밀지 않아도 그네가 나한테 오는 것을 반복하는 주기 혹은 진동수 주기라고 할게요 그리고 내가 손으로 그네를 미는 주기음 시간이 두 개가 있는 거예요 그 두 주기가 같아지면 그네의 진폭이 커지죠 그렇 아 강화 되겠네 강화 되겠네 그래서 그 사실 생각해 보 뭐 직접 실험하지 필요는 없고 생각해 보시면 예를 들어 커다란 뭐 밥사발 같은 곳에 엄청나게 커다란 뭐 쇠구슬이 있다라고 생각해 보세요 최고수를 밀어서이 밥사발 밖으로 우리가 밀어낼 수 있어요 예 밀고 아 살짝 오다가 갈 또 살짝 더 밀고 어 규칙적으로 계속 밀면 밀고 피했다가 밀고 피했다 그러면 계속 진폭을 크게
(18:07) 할 수 있을 것 같잖아요 그게 그냥 국명 현상이에요 그러니까 우리 우리 집에 있는 유리창도 가만히 있는 녀석 같지만 사실은 지혼자지고 하고 있다는 거죠 맞습니다 예 요게 그거랑 같 스피커에서 나오는 거랑 우연히 같아지면 맞 다다다 이러는 갑자기 맞아요 그럼 같은 애들만 움직이는 거예요 예 진동수가 같 애들만 아 그래서 그 그 아마 찾아보시면 목소리로 와인장 깨는 사람 있거든요네 목소리로 뭘 와인잔을 놓고 목소리에음을 조정해 갖고 와인잔을 계속 떨리게 해서 와인잔을 깨는 사람이 있어요음 인터넷 유튜브 찾아보시면 있습니다 그러면 그 사람은 진동 폭을 여기 맞춰서 맞춰 보는 거예요 예 그래 그게 딱 맞으면은이 와인잔이 점점점점 크게 떨리다가 심지어는 부서지기도 해요 그게 가능한 그러면 통돌이 세탁기 돌아가다가 르 돌아가다가 마지막에 쓸 때쯤 되면 오히려 세탁기 기하는게 어 그것도 비슷한 거가 그것도 비슷해 그것도 비슷한 거예요
(19:10) 그 사실 그런 얘들이 진짜 많아요 그 요즘은 아니고 예전에 세탁기 껍질이 진동하고 있었구나 그 그 그렇죠 예전에 라디오 주파수 맞출 때 예전에 이게 다이아를 돌렸지요 그것도 사실 전자기 적이긴 하지만 똑같아요이 외부에서 오는 라디오 방송사가 가 보낸 전파의 주기가 있고음 그다음에 제가이 다이어를 돌리면 전자 회로 안에서 만들어질 수 있는이 전자기파의 주기 진동시 조정하는 거거든요 그 두 개가 맞으면 공명 때문에 딱 그 신호가 커지죠 아 예 옛날 들었던 기억이 있다 그 그럼 그러면 님 예를 들면 스피커에서 진동을 막 스피커가 진동 보냈어요 근데 유리창은 그 비슷해서 떨려요 근데 사람은 그 진봉 폭이 안 맞지 않습니까 그럼 거기서 사람이 그 진봉 맞으면 진 의 폭이 줄어 그러니까 소리가 더 퍼져야 되는데 앞에 뭐가 있어요 진동폭이 서로 안 맞는 물체가 앞에 있으면 소리가 줄어들어야 되겠네요 소리가 줄어들겠죠 왜냐면 진동폭이 방해를 받으니까 강화되지 않고 예 그런데 이게 조금 다른
(20:13) 얘기긴 한데요 그 낮은 음의 소리들 있잖아요 그럼 파장이 굉장히 커요 그래서 사람 정도가 앞에서 있다고 해서 유리창에 그 소리가 전달되지 않지는 않 고파면 달라도 히 민감한데요 소라 고등 이런 거 뒤에다 딱 대면 막 바닷 소리 같은 거 우하고 들리잖아요 이게 무슨 스피커도 아닌데 왜 들 그 왜 그래요 그럼 그것도 관 있니까 공격 이것도 진동이 없잖아 진동이 보내는게 없잖아요 있어요 우리가 듣지 못해서 그렇지 이걸 우리 주변에 소음을 녹음을 해서 보면 여러음을 여러 진동수를 갖고 있는 소리가 함께 다 있어요 그리고 그래서 우리가 백색 소음이라고 잖아요 아 그니까가 있 그 빛은음 여러 여러 진동수의 빛이 다 모이면 흰색이 되잖아요음 소리를 거기에 빗대서 여러 진동수의 음이 소음으로 있는 것 그걸 백색 소음이라고 해요 근데 백색 소음은 그래서 여러 음의 음들이 소리 음의 여러 높이를 갖고 있는 음들이 섞여
(21:17) 있는데 말씀하신 것처럼 소라 껍데기는 소라 껍데기 크기가 정해져 있잖아요 그래서 소라 껍데기 정도의 고유의 진동수가 있는데 예 그 고유 진동수가 있고 바깥은 탁 온갖 진동수가 다 있고 그중에서 같은 것만 증폭을 시키니까 와우와 이렇게 들린다는 그래서 이거 만약에 제 믿기지 않으시면 그거 해 보시면 돼요네 큰 컵하나 작은 컵을 귀에 대보세요 예 그러면 예상을 해 보세요 웅하는 바닷 소리의 소리의 높이가음음 서로 다르겠나 달라요 해보시면 작은 큰 족에 작은 조개에 아네 맞아 그 작은 컵은 혹은 작은 조개는 높은 음의 바다 소리를 들 큰 거는 진복이 큰 걸로 그 채팅창에 그런 PD 님들이 물어본 건데 들어온 전파 방에 쏘는 거 있지 않습니까 슨 총 쏘는 거 그런 것도 비슷한 원리예요 전자파 전 그건 좀 다른가 건가요 그건 제가 잘 모르겠는데요 근데이 도움은 분명히 될 거예요 그게 그 드론 내의 회로가 이용하고 있는
(22:23) 교류에 진동수를 하고 정확한 진동수를 갖고 있는 전자기를 를 이용하면 그게 교란이 될 여지는 훨씬 크죠음 야음 혹시 예 사랑도 어 그런 겁니다 진폭이 같은 거예요 같은게 맞 파수가 같아야 맞는 거야 가슴이 계속 뛰니까 뭔 이게 진동수 갈 텐데 그 같은 진동수가 느끼면 같이 강화되는 거고 그렇지 그러다 보니까 내가이 사람 옆에만 갔는데도 가슴이 더 큰 흥 뜨는 거지 더 마치 전 그 스피커 올 유리가 다 하는 것처럼 하이 아 근데 지금 말씀하신게 좀 근거가 있는게 사랑 정도는 아니고요 사람들의 뇌 팔을 요즘은 정교하게 측정하거나 서로 예를 들어 함께 노래를 하는 예를 들어 재즈 음악가들이 서로 막 그때그때 실시간으로 음악을 서로 맞춰 나가잖아요 그런 사람들의 뇌파를 측정하면 뇌파가 이렇게 같이 진 그 공명하는 걸 관찰하기도 돼요 우와 그 재밌는게 심지어 교수가 수업을 하는
(23:29) 학생이 집중해서들을 때 그때는 교수와 학생의 뇌파도 이렇게 동기화가 돼서 같이 그래서 사랑은 그런데 어떤 고유의 진동수가 있는지 잘 모르겠어요 사은 모르겠고 사랑도 그렇겠죠 손 잡으면 왠지 더 떨리고 그 더 떨리고 그런 거 있어 괜히 집에 가서네 당신 혹시 나한테 할 얘기 없어 이러면 어 거지 저는 그 질문보다 가끔 예 그 여보 오늘 나 뭐 변한 거 없어 그러면 그게 그 아 어 그때 진짜 무섭죠 진짜 빨리 알아내야 되는데 누가 와서 살짝 귓속말로 얘기해 주면 한 5만 원 줄 거 빨리 도대체 모르겠는데 뭘 얘기 소 보이다 것도 안 보여 빨리 맞춰니까 와 아 그 다음에 또 얘기 더 할까요 예네 그다음 말씀드릴 거는 그 현수선이라는게 있는데요 현실 예
(24:34) 현수선 별게 아니고요 그냥 뭘 이렇게 늘어뜨린 거예요 그 PPT 그 저기 자료를 보셔도 되고요 이렇게 갖고 온 걸 보셔도 되고요 현수선 저건 뭡니까 이게 이렇게 모양을 이렇게 같게 그 처진 빨 처진 빨랫줄 아 정확히 터진 빨랫줄 정확 한수 선이라고 불러요 예 현수가 뭐냐면 늘어 줄을 그 늘어뜨렸다 뜻이에요 수교하고 하잖아요게 예 현수교가 정확히 똑같아요 한체로 근데이 현수 선을 요렇게 한 다음에 이걸 잘 해서 렇게 뒤집어요음 뒤집어요 뒤집어도 문이이 모양이 안 무너지잖네 예 예 어 잠깐만요 예 원래는 늘어뜨리는 건데 아니 얘가 그렇죠 이렇게 늘어뜨려 거아 근데 이걸 제가 이렇게 이렇게 뒤집어요 어 근데 왜 그래도 안 르 저건 구 구슬길 연결되 있는 거라서 구슬들 그리 서로 서로 의지해서 그렇죠 아치의 효과처럼 그걸 제가이 PPT 그림으로
(25:39) 그려봤는데요네 이거를 예 그 걱정하지 마세요 설명 자세히 안 해요음 막 수식이 나오고 하는데 아 그 제책이 물리 장난감을 보시면은 여기 보면이 옆을 보시면 이렇게 빨간색으로 보이는 면들 있죠 거기가 일종의 경고 페이지예요 경고 거기 보면가 수 다 아 어려운 내용들 혹시 그 사서 보시는 분들은 좀 너무 수학적인 내용이 어렵다고 생각하시면 그 부분은 건너뛰어서 보셔도 되고요 거기에 관심이 있다 그 괜찮습니다 알겠습니다 수식 그도 좀 보여주세요 예 PT 현수선 보시면 위에 있는 모습이 아까 처음에 그냥 우리가 늘어뜨린 그 빨랫줄 예 그거잖아요 여기서 보면 제가 분홍색으로 표시한 부분 있죠 가운데 그 부분에 작용하는 힘을 를 생각하면 제가 FG고 적은게 아랫 방향의 중력이 중력은 아랫 방향이고 그다음에 왼쪽과 오른쪽에 줄이 매달려 있으니까 얘가 잡아당겨요고 부분을 예 그런데이 전체를 뒤집은 아래 그림을
(26:44) 보세요네 아래와 위에 그요 부분을 뒤집으면요 요기가 된 건데요 위와 아래 그림을 비교해 보시면 중력의 방향이 아래가 반대 예 그래서 화살표가 바뀌죠 방향이 한편 줄이 줄의 다른 부분이요 부분에 미치는 힘은 이때는 방향이 반대가 되죠 그렇네요 그래서 위하고 아래에서 모든 힘의 방향이 바뀌어요 예 완전히 정반대로네 그러 그러면 물리학에 어떤 부분에 작용하는 힘을 다 더했을 때 힘의 총합이 0이면 그러면 그 상태가 안정적으로 유지되거든요 그 얘기는 위에서요 부분이 안정적이라면 뒤집어도요 부분도 안정적이어야 되는 거죠음 그래서 현수선 늘어트린 다음에 뒤집어도 안정적인 구조가 돼요 플러스 마이너스가 서로 바뀐 거지 플러스 마이너스 바뀐 거지 똑같다 합치면 0인 건 똑같다 맞습니다 그래서 사실 이걸 이용을 해서 건축하는 사람이 그 유명한 아마 들어보셨을 그 스페인의
(27:51) 위대한 건축가 가우디 있니다 오 가우디는 건축가가 예 그 성당에이 도움을 설계할 때음 이 돔이 안정적으로 모양이 유지돼야 되잖아요 그래서 그 사람이 보면 작업실에서 이걸 늘어 예 거꾸로해서 설계를 해요 이렇게 늘어 다 뭘 이렇게 늘어 매달아서 늘어 태 다음에 예 그다음에 교회를 만들 땐 이걸 뒤 뒤집어서 그냥 달면 되는 거요 예이야이 현수선 갖고 제가 재밌는 그 그 경험이 있는데 처음에 제가 아까 제가 했던 요거는 여기 낚싯줄을 한 거거든요 근데 처음에는 낚싯줄 이 잘 안 보여 갖고 고무줄로 했어요 고무줄로 예 이게 마스크 줄을네 마스크 줄도 당연히 이렇게 늘어 세우면 이렇게 늘어지는 모양이 됩니다죠 예 마스크 줄은 뒤집으면 어떻게 될까요 안정적일까 안정적이지 않을까요 늘어나니까 아니 근데 저거는 양쪽으로 당기는 힘이 달라질 거 같은 생각이 드는데 이게 재밌는게 똑 같은데
(28:55) 아니요 이게이 고무줄은 응 이 부분에 항상 이걸 그 어떻게 되죠 안쪽으로 미는 힘을 작용하나요 그 힘은 뒤집어도 안 벗기 오라라라 오라 어 아까 PPT 다시 한번 보세요 어 잠깐 잠깐 잠깐 잠깐 잠깐 뭔가 변화 그 아까 전에는 위에 이렇게 현 수선을 했을 때 그냥 낚싯 줄이니까 바깥으로 당기는 힘만 있었는데 여기는 고무 줄이니까 당기는 힘과 무슨 반대되는 힘이 같이 있는 거 같은데이 기는 미는 힘과 당기는 힘이 같이 있는 거 맞 그런데 지금 말씀하신 고무줄 때문에 서로 안으로 잡아당기는 힘은 뒤집어도 여전히 안으로 다빠 당기는 힘이죠 아 완전히 반대로 돼야 되는네 예 어 금방 이해하셨나요 아 그 아까 피트에서 보면 낚싯줄로 하면 괜찮거든요 근데 고무줄로 하면 줄 자체에 힘이 없으니 없으니까 아 진짜 신기하다 야 야 처음에는 근데 그 생각을 못 했어요 그래서 고무줄로 한 거예요 처음에 지 아니 이게
(30:00) 왜 나중에 생각해 보니까 재밌더라고요 새로운 발견이네요 오히려 그 낚싯줄로 해야 돼 고무줄만 하면 안 돼요 아 이게 뒤집으면 고무줄의 경우에는이 안쪽으로 작용하는 힘이 똑바로 있을 때나 뒤집어 있을 때 그게 방향이 똑같고 계속 당기는 힘은 같 중이면 다른 힘은 다 바뀌고 그래서 상황이 달라지는 거죠 아 아까 낚시처럼 모든 힘이 방향이 반대가 돼 그니까 중심점이 달라진 거군요 이름바 어 아 그래서 이게 처음에 고무줄로 해서 면 했다고 생각했는데 나중에 보니까 나름 고무줄서 또 배운 거더라고요 고무줄 라면 안 된다는 거 실수에서 배운 와 물리학이 어마어마한 야 재밌다 되게 신기하네 우리 생활에 이렇게 물리 원칙이 많이 있었습니까 야 근데 이런 거를 이런 걸 가르쳐 주지 왜 물리를 이런 걸 안 가르쳐 주고 어 뭐 뭐 구하시오 시간이 한시간 갔을 때 얼마 됐 안성찬 일어나 너 운동 에너지 공신 뭐야 1데 그 위치 에너지는 뭐야 아 근데 그것도 필요해요 그 운동 에너지 공식
(31:05) 같은 것도 필요한데 제가 저도 대학에서 학생들을 가르치면 안타까운게 막 수식으로는 막 잘 풀어요 근데 그게 예 우리 주변에서 무슨 의미인지는 잘 생각을 못 해 보는 학생들이 많아요 그럴 때 이런 장난감들이 도움이 많이 되죠 야 진짜 물리학 대박이다 요즘 중국요 응 국가에서 물리학 그 우선한 되잖아 물리 물리학 학생들을 우선해서 뽑는다고 하니까 공부 좀 잘하는 애들은 그냥 다들 물리학과 간다고 난리라는데 죠요 어디서요 중국요 맞아요 저가 중국에 아는 교수들이 조금 있는데 어 좀 무서워요 요즘 그 물뿐 아니라 모든 학문 분야에서 엄청나게 중국이 빨리 발전하는데 그것 중에 이유 중에 하나가 젊은 학생들이 아직도 과학을 하려고 하는 학생들이 많 과들은 필수 과목처럼 물리를 중국에서 넣어서 예를 들면 역사 우리 거의 필수 과목처럼 하잖아 구경수 역사 이런 거 필수 과목처럼 하잖아 구경수 역사 물리 걸 필수 과목으로
(32:09) 했더라고 거의 예 뭐 안타깝지만 해 맞습니다 예네 그렇지 물리학은 그 이게 아름다운 거 같아요음 그러니까 빨간색 공을 떨어뜨릴 때의 운동 에너지와 파란색 공을 떨어뜨릴 때 운동 에너지 요즘 거기 너무 집착한 거 같 물리 같아 같죠 같아 근데 우리 현실로 돌아오면 어 달라 어 각자 달라 달라 아 맨날 요즘 그러니까 채팅창에서 느는 도대체 파란색인지 빨간색인 알 수없 그 왜 느의 정체를 밝혀라 어 그렇지 우린 정체가 없는데 아 그게 글쎄 그게 아름다운 겁니다 이게 그 어느 쪽에 적용해도 항상 같이 적용되는네 알겠습니다 또 다른 거 하나 더 알려주십시오 현실 세계에서는 우리 보스가 그랬으면 괜찮고 남의 보스가 그랬으면 이상하고 그 그 되 물리 그런 거 없어요 어 항상 똑같다음 그 물약은 말씀하신 그런 장점은 있죠 물약은 아니라 과학들이 그런데요 서로 이렇게 토론을 하다가
(33:15) 토론 상대와 내가 함께 합의할 수 있는 것이 있다라고 그걸 가정하고 토론을 하거든요 그 대부분은 그게 맞고요 근데 과학이 아닌 다른 분야에서는 그렇죠 그러 무엇이 옳지가 중요한지는 잘 생각 물리학자들이 이렇게 토론하면 네가 틀렸구나 그게 명게 하겠어요 네가 틀렸네 네가 그거 생각을 못했네 근데 대부분은 둘 다 모아놓게 많아요가 국사 시간에 옛날에 예 배우다가 선생님 어 왜 우리나라가 여진을 공격할 때는 여진 정벌이 하고 외구 우리나라로 들어오는 건 외구의 범이라고 합니까 범이라면 우리가 여진족 공격한 것도 여진 침범이 와 우리 그 정 공격을 정벌이 한다면 외국가 한반도를 정벌 했다고 해야지 왜 그때그때 다른가요 어라고 했다가 예상된다 쓸데없는 지문고 있어 니 알고 묻는 거야 모르고 묻는
(34:23) 거야 아데 그래서 그때부터 역사가 싫었어 문이 그래서 싫 예 알겠습니다 다음에 보여 드리려고 갖고 온 건 팽이 중인데요 팽이 제가 팽이를 세 개를 갖고 왔는데 이것도 무게 중심과 관련된 건가요 무게 중심보다는 이거 가군 동량 뭐 그런 건데요 사실 아 이게 가군 동량이 이게 대학교 물리학에서 꽤 중요한데 그 고등학교 과학에서 배우질 않고요 그래서 사람들이 익숙하지 않아서 어 예 궁금하신 분은 제 책에 자세히 나오고요네 오늘은 자세한 설명 을 안 하고 그냥 팽이 보여 드리는 정도로만 기하겠습니다이 이거 보이시나요 어 아주 작은 작 팽 이게 꽤 비싼 팩입니다 왜요 이게 작은데 일본에선이 팽이가 얼마나 오랫동안 안 넘어지고 도는지 대회가 있어요 그 대회에서 우승한 팩입니다 어 작으면 잘 안 넘어져요 작다보니까 이거 정교하게 만들어야 돼요 한번 이걸
(35:26) 제가려 볼게요 예음 카메라가 잡힐지 카메라 위에서 한번 보여 줘야 되는데 잘 안 잡힐 것 같긴 한데 그래도 한번 해 봐 주 해봐 주세요 자가 볼게요 예 그게 평범한 거 같은데 모르겠네요 그냥 돌 계속 돌고는 있는데 오래 도는 팽이는 왜 오래 돌아요 오래 무게 중심을 잘 잡아서 정확히 좌우 대칭이 돼요 정확히 아 아주 한가운데로 딱 찍어서 그렇죠 그리고이 바닥에 닿는 그 부분이 찰 마찰이 예 근데 사실 제가 보 되게 오래 돌 오래 돌긴 하는 거 같네 옆으로도 안 돌고 그대로서 있거든요 이게 잘 아 꽤 오래 오래 도니까 좀 기다려 보죠 뭐 예 그 사이에 이것도 때 볼까요 이것도 꽤 재밌는 팩인데요 이거는 돌리면 아 초점이 잘 안 맞네요 그죠 저 저 저번 작아 가지고 거기다 그냥 해해 봐 주십시오 예 쟤는 얘는 완전 얘는 완전 아닌데요 얘는 굉장히 싼 거 같습니다
(36:29) 팽이가 혹시 국산야 돌다가 뒤집어져요 아 이건 팽이의 뭔가 중심점을 완전 어 어 섰어 거꾸 섰어 아 저게 말이대 돌다가 뒤집어지는입니다 아 저렇게 디자인 된 거예요 그니까 돌다가 뒤집어지고 만들어 만들어진 이게 왜 뒤집어 지는지 그것도 굉장히 재밌는 이론이 있는데요 그 설명 짧은 시간 해드리기 좀 어렵고요 때 해 주세요고 이게이 바닥이 조금 그런가 이게 쉬나 이게 굉장히 멋있거든 그래서 옆에서 보면은 흔들리지도 않고 똑바로서 있는 것처럼 보이거든요 예음 이게 제가 갖고 오다가 걸 휘나네 어쨌든 일단은 두고요 그다음에 이거는 그 터키 팽이라고 불리는 팩인데요 이거는 이렇게 들고 있다가 제가 이걸 놓으면은 위아래로 예 옆으로 되는데 오 우와 여기서 좀 유심히 볼게 두 가지예요 하나는 얘가 도는데 그냥
(37:35) 이렇게 돌죠 옆으로네 그 이렇게 안 되고 그러면 얘가 돌면서 이게 돌아요 전체가음 아 다시 보세요 야 옛날에 그 저 실로 감아서 팽이 했던 거 기억나요 어 어어 그런 거 했죠 저거 터키의 팽이에 터키 팽이 터키 사람들이 갖고는 팽이라고 아 돌 돌지 돌지 돌지 음 몇 가지가 있네 일단 얘가 원 생각하면 옆으로 돌면 얘가 왜 안 이쪽으로 안 돌아가지고 생각하잖아요 이게 사실 그 가군 동량 보존이라는 것에 관계가 되는데 사실 자 그 자전거 바퀴 생각하셔도 돼요 자전거 바퀴가 빨리 돌면 잘 안 넘어지자 좌 안 넘죠 그거랑 갖고 얘가여 이렇게 돌아가는 거 그건 세차 운동하고 관계 돼서 지구도 자전축이 천천히 돌잖아요 그게 색사 운동이라고 하는데 그거랑 관계됩니다 어 그래서 팽이는 일단 이렇게 보여 드리는 정도로 저 넘어 저 작은 팽이는 얼마예요 오 저기 얘기하면 안 돼요 대략 지금 제 아내가 방송을 본 오늘
(38:38) 본다 그랬거든요 예 그래서 얘기하면 안 돼요 당근에서 샀다고 해요 당근에서 전가 전가 정가 전가는 얼마다 근데 난 싸게 샀다 야 이거는 완전 돈 본 거야 당 당 때 정말 당근 덕분에 수많은 남자들이 그 그 그럼 되지습니까 별로 안 비쌉니다 예 와 근데 저거는 제가 보기엔 대단한 물리가 아니고 그냥 가운데를 잘 찍은 거 예 공학적인 성과인 거죠 그냥 공학적인 성가인 거죠 걸 굉장히 정교하게 만들어서 근데 오늘은 뭔가 컨디션이 안 좋네요 평이가 이거 이게 정말 재밌는데 슬라이드 사진에 보면 딱 가운데로 있 예 이게 그냥 그대로서 있거든요이 세차 운동을 안 하고 그래서이 팽이를 슬리핑 탑이라고 불러요 잠자는 팽이 어 그래서 이렇게 보면은 도는 것도 안 보이고 똑 고하게서 있다 이거죠 아 그인 인셉션이 영화에 보면은 팩 있잖아요 그것처럼 돌아요 예 그거 아침에는 한
(39:43) 번은 그렇게 도는데요 자꾸 돌리면 잘 안 서요 왜 왜 왜 왜 아니 좀 전에 슬리핑이라서 아니 좀 전에 서서 쫙 짝하고 나면 두 번째는 잘 안안 금방 죽고 금방 죽고 와 자국 이러면 내일 아침에 또 잘 돌 거예요 아 슬리핑 슬리핑 팽이 잠자는 팽이 아 아 꼬꼬이서는 거고 저 저거 설명해 주 저 제 거꾸로 뒀다가 뒤로 도는 애음 저 뒤로 도는 애 있지 않습니까 이게 아 이거 설명이 좀 어려워요 아 해 주세요 그래도 저 아 저거 저거 저거 왜 왜 왜 저 왜저렇게 할 수 있 이게 이쪽은 넓죠 네네 돌다가 처음에가 이렇게 똑바로 돌다가 찰 아 그러다가 얘가 충분히 이렇게 넘잖아요 그러면 얘가 거꾸로 되고 그렇게 되면 여기는 한 점이아닌 에서 작용하는 토크 마찰력에
(41:00) 의한 토크 같은 걸 잘 고려해서 생 생각하면 설명할 수 있는데 이렇게 아 저도 수직으로는 봤는데 말로 이렇게 쉽게 설명하기 어렵더라고요 이거 어쨌든 물약으로 설명할 수 있는 현상입니다 아니 그러면 교수님 이거 팽이 회사들은 팽이를 말듯 때 이렇게 물리적인 계산을 한 다음에 그러고 만들까요 그러면 팽이들 우리 우리가 팽이 장 팽이들 만나 그걸 이제 계속 하해 보다가 그냥 어 거 잘 도네 예 잘 팔리면 계속 그 방식으로 만들겠죠 사람들이 그런 걸 정교하게 계산해 설계했을 가능성도 없을 것 같아요 이렇게 해보고 저렇게 해보고 하다가 그 예전에 집에서도 뭐 동네 아이들이랑 팽이 치기 하면서 놀 때 이렇게도 깎아보고 저렇게도 깎아보고 하다가 아 이렇게 하면 되겠다라고 하는 거죠 그걸 정교하게 생각했을 것 같지요음 요거는 그러면 무슨 팽이는 무슨 물리학의 원 원리가 있 각 운동 각운동 운동이라는 건 뭐 뭐 뭐예요 그 운동량이라는 물리학의 개념은 질량
(42:04) 곱하기 속도거든요 그 사실 운동량을 제일 쉽게 설명하는게 누가 제 군밤을 때리면 어떨 때 아플까 그래 생각하면 되거든요 세게 때릴 때 세다는게 뭘까요 속도가 빠를 때 그렇죠 그리고 질량이 클 때 그렇죠 맞아요 그래 질량고 속도가 곱해진 양이 운동량이 그걸 운동량이 큰 무언가로 군밤을 누가 때리면 아픈 거죠네 그게 운동량의 개념이에요 운동량 예 그런데 각 운동량은 운동량은 뭐가 이렇게 움직이는 것에 관계된 운동량이아요 각운동량은 회전하는 거에 관계된 운동량이음 그래서 그건 다른 물리적인 원칙이 적용됩니다 비슷한 원칙이기 해요 그래서 어떤 더 무거운게 더 빨리 돌면 아 그러면 가군 농약이 커요 가군 용량이 커진다 그것도 질량 질량 곱하기 속도 근데 질량이 아기보다 그걸 관성 모멘트 부르는데요 그 그 아 질량은 뭘 움직이려고 하는데 잘 안 움직이려고 물체가
(43:09) 버티는게 질량이아요 그 관성이라는 걸 관성 모멘트는 돌리려고 하는데 얘가 안 돌 안 돌아가려고 뻗대는 정도 돌아가 아음 설명 싶다 그런 건데 억지로 돌리면 힘이 세지는 거군요 그러니까 그렇죠 그걸 억지로 돌리면 힘이 세지요 그래서 관성 모멘트 좀 좀 쉽게 이해할 수 있는게이 기다란 막대기를 한쪽 끝을 잡고 돌리면 돌리기 어렵잖아요 한편 가운데로 잡고 이렇게 돌리면 돌리기 쉽죠 그래서 가운데를 잡고 돌릴 때가 관성 모멘트가 작고 한쪽 끝을 잡고 돌릴 때가 관성 모멘트가 커요 아 그 말씀하신 것처럼 관성 모멘트가 큰 걸 빠르게 돌려서 때리면 많이 아프죠 많이 아프죠 그래서 그 무협 영화 보면 그 무술의 고수들도 이걸 다 알고 있거든요 긴 봉으로 어 그 상대방이 공격이 공격하려고 할 때 막 겁주는 용도로 빨리 막대를 휘두를 땐 항상 가운데 잡고 들려요 그렇죠 때릴 때는 때릴 때는 끝을 잡고 때 끝을 잡고 때리고 아 그래서 무술의 고수들도 다군 동량 뭐 관성 모멘트
(44:15) 그걸 다 알고 있는 겁니다 그렇지이야 그렇지 그렇지 아 그 야구 야구도 정교하게 쳐야 될 때는 배트 짧게 잡고 추 음음음 그것 같은 원리죠 맞아요 정확히 그래요 그래서 홈런을 때리려면 길 길게 잡아야 되고 그다음에 짧게 잡으면 정확히 그래요 그래서이 공이 올 때 거기에 내 내가 휘두르는 배트의 위치와 속도를 조정하는게 훨씬 편하죠 편하죠 어 번트 될 때 배트 끝을 잡고 번트 되면 바보지 어 그렇지 그렇지 그 이렇게 잡아음가 얼 모 은 진짜 아름다운 학문입니다 물리학으로 설명이 안 되는게 없네 와 아니 꼭 그런 건 아니고 제가 설명할 수 있는 것만 갖고온 거죠네 와 알겠습니다 막간을 이용해서 인셉션 팽이를 검색해 봤거든요네 똑같아 교수님 혼 나실 만하네요 왜 엄청 비싸 아니 아주 아주 비싸지 아니
(45:20) 그이야 저게 아 그 원래 그런 거였어 왜 영화 인셉션에서 한번 돌리면 안쓰 쓰러지니까 야 이거는 꿈인 거야 현실에서는 쓰러지는데 이게 안 쓰러지니까 이건 꿈이네 그 용도로 돌리는 건데 맞아요 근데 그것도 제가 좀 생각해 보니까 재밌더라고요 근데 거기서도 사람들이 이렇게 걸어는 다니잖아요 근데 팽이가 영원히 안 쓰러지는 세상이면 마찰력이 없다는 얘기거든요 마찰력이 없으면 우리가 걸어가지 못해요 걸어가지 못한다고요 예 우리가 걷는 이유는 제 발이 땅을 밀면 땅이 제 발을 앞쪽으로 밀기 때문에 우리가 걸어갈 수 있는 거거든요 그래서 얼음 위에 완벽하게 매끄러운 얼음이 있다 그러면 거기서 앞으로 못 가요 못가겠네 제자리에 겠네 제자리에 마찰력이 있어야 그걸 그걸 딛고 앞으로 가니까 제가 그 얘기를 하면서 따라서 인셉션은 이게 그 모순이다음 팽이가 영원히 넘어지지 않는 세상이라면 그 꿈속에선 거기 등장 인물들이 앞으로 걸을 수도
(46:25) 없어야 한다라고 했던 누가 그게 꿈인지 아닌지를 판단하는게 그 모순이 있다는 걸 보여주는 거다라고 누가 얘기하 그러면 운동화도 바닥에 마찰력을 훨씬 강하게 하면 잘 나가겠네요 앞으로 그죠 예 어 미끌미끌 하지 않고 그래서 그 그 뭐죠 포뮬라원 같은 자동차 경주 그때 마찰력이 굉장히 큰 타이어로 써요 어 앞으로 잘 나가라고네 그래서 가속도 잘되고 커브를 돌 때 미끄러지지도 않고 예 그다음에 뭘 할까요 뭐든지 보여 주십시오 아 이거 먼저 할까요 예 순서가 일단 예 이거 먼저 할게요 예 이게 사실 제가 이걸 갖고 왔는데 그 여러분들이 집에서 예 탁구공고 헤어드라이기로 해도 돼요 예 탁구공 위로 올리는 거 어 사실 제가 바람을 불면 얘가 저거 옛날에 저런 장난감 많이 있었는데 파는 거 파는 거 많았습니다 저거 처음 봤어 어 처음 봤다 불면 탁구공이 위로 공중에 떴다가
(47:30) 제자리 오고 하 공중부양 되는 거예요 저런 장난가 많이 있었어요 저렇게 이게 사실 그 만지 경험하시는 이거 꽤 재밌어요 이게이 위치에서 계속 머문다는 얘기는 얘가 아래로 내려가려고 하면 밀고 위로 올라가려면 내려간다 이쪽 방향으로 이쪽도 재밌어요 얘가 옆으로 가려고 하면 안으로 미니까 얘가 벗어나지 않는 거거든요 안으로는 왜 밀 바람을 불 위로는 올라가는 건 알겠는데 왜 옆으로도 안 좌 이게 꽤 재밌는 문제예요 어 예전에 해봤는데 왜 그런지는 생각을 안 해 봤네 일단 이쪽 방향으로 이건 쉽거든요 얘가 여기 있든 여기 있든 아래 중력은 얘를 아래로 내리잖아요 그런데 아래쪽은 위로 미는 바람이 힘이 크죠 그래서 충분히 많이 내려가면 바람이 세 지니까 올라가요 그다음 충분히 올라가면 바람이 약해지니까 내 그래서 위아래에서 방향으로 여기에 어떤 평 위치가 있죠 예이 옆은 뭘까요이 옆은 재밌는게 이걸 그 유체 역학에서 베르누이 원리라고 하는데요 몸가
(48:35) 속도가 굉장히 빨리 바람이나 그 물의 흐름이 빠르면 그곳이 압력이 낮아져요 압력이 낮아지다네 사실 그걸 옆으로 이게 흐르는 거잖아요 바람이 공의 옆으로 흐르는 건데 안력이 낮아요 제가 그걸 지금 깜빡하고 안 갖고 왔는데요 그 어 집에 뭐 뿌리는 장치 보면음 옛날에 향수병이 그런게 있었는데이 뒤를 고무 부분을 자꾸 누르면 칙칙 누르면은 향수가 나오잖아요 그때 어떻게 그 안에 구조가 돼 있냐면이 관이 이렇게 균일하게 돼 있는게 아니라이 향수 액체가 올라오는 부분이 이렇게 관이 좁아요 예 그러면 이렇게 공기가 들어오다가 관이 좁은 데를 지나가야 되니까 고기 빨라지거나 빨라지면 고기가 압력이 낮아져서 와 아 예 그래서 중요한게 그 바람이 바람의 속도가 빠른 곳이 압력이 낮다고 생각해서요 바람이 빠른 곳은 왜 압력이 낫습니까 그게 베르누
(49:39) 원리인데요 예 자세한 내용은 그 김범주의 물리 장난감에 나옵니다 예 력 낫겠지 뭘 빨리 밀 밀어내니까 그런가 뭘 빨리 그 사람이 빨리 불면 순간적으로 여기에 있는 공기 입자들 같이 빨려서 나갈테니까 그래서 그런가요 여기는 공기 입자의 밀도가 줄지 적지 겠어 이러면 확 쳐서 올리면 뭐가 뭐가 뭔가 있었는데 뭔가 없어서 그런가 보통 이걸 그 물리학에서 에너지 보존 법칙으로 수식으로 증명을 하거든요네 근데 그 의미가 뭔지는 저도 제 생각을 많이 안 해 봤네요 음음 그럼 아까 저 말씀하신요요 드라이기나 바람 오는 건 밑에서 바람을 불어 올리니까음요요요 길은 압력이 낮아서 그죠요 길에서 양옆으로 움직이려고 하면 이쪽도 압력이 세서 못 가고 이쪽도 압력이 세서 못 가고 꼭 가운데만 이렇게 가운데 압력이 약 가둬 효과가 있는 거야 가지는 효과 아까 위아래 방향은 이제 바람의 속도가 아래는 빠르고 위는 흐 느리고 중력은 아랫 방향으로 설명하고 방금 말씀하신게 정확해요 옆으로 벗어나지 않는 건 여기가 압력이 낮고이 바깥쪽
(50:43) 둘레 다 둘러서 압력이죠 그 벗어나려고 하면 압력이 낮은 쪽으로 가려고 하고 이쪽으로 가려면 또 이쪽으로고 그래서 그냥 이게 무슨 정교한 장치일 필요도 없거든요 여기서 바람만 그냥 나오기만 하면 얘가 막 왔다 갔다 하면 보자 여기가 부니까 압력이 하면 옆에가 이렇게 몰려드는 효과 이렇게 불면 뭐가 몰려드는 효과가 근데 튀어나가는 건 왜 그래요 그러면 불고 있으면 안 빠져 나가야 될 거 같은데 안안 안 빠져 나가죠 제가 불 부는 걸 멈춰 많 불다가 멈추니까 그러는구나 분대도 다 에어컨 바람 아 에어컨 바람 때문에 그럴 수 있겠다 이거 유체 역학으로 설명할 수 있는 재밌는 장난감이죠 야 야 진짜 신기하네 뭐든지 저게 비행기 날아가는 거하고 관련이 있습니까 그게 아 이게 참 참 그 어려운 문제인데요 예 문제가 아직도 물리학과의 일반 물리학 교과서에 비행기가 뜨는 원리를 베르누이 원리
(51:48) 아까 얘기한 그거로 설명해요 근데 사실 그게 비행기가 뜨는 것에 일부 도움은 되지만 베르누이 원리만으로 비행기 이 날개가 작동하는 거 설명하는 거 사실 문제가 있어요 사실 그것보다 간단한게 그 그냥 그 예전에 우리 연 날리는 거 생각해 보시면 연 그냥 이렇게 종이 판이 아아 예 근데 실을 자꾸 뛰면 얘가 뜨잖아요 사실 그거를 그냥 설명하는게 맞아요 이거는 뉴턴의 작용 반작용 법칙이라고 하잖아요 얘가이 이런 그 각도를 갖고 있는 물체가 이쪽으로 가면 얘가 공기를 밀아 그럼 공기는 얘를 반대로 미는데이 방향이 있으니까 이게 미는 힘으로 뜨 올다 그 사실은 베르노의 원리로 설명할 필요는 없어요음 근데 그 물리학과 교과서에는 지금도 베르노의 원리라고 나오는 걸 예 그 그 전에 그 민태기 박사님 그분하고 잠깐 얘기를 나눴었는데 그 굉 안타까워 하더라고요 베로니 원리가 비행기가 뜨는 것에 가장 중요한 원칙
(52:52) 원리는 아니다 그 수학적으로 보이는 아 무슨 이론이라고 있는데 저도 공부는 안 했어요 그래서 지금 설명드리기 조금 어렵고요 근데 그냥 뉴턴의 작용 반작용 법칙만 어느 정도는 설명이 돼요 그게 더 중요할 가능성이 크죠 야 그 우리 분명히 빈태 박사님한테 들었는데 또 기억이네 그때도 그때도 아이슈 타인도 잘 몰랐다는 제가 저도 비행기가 왜 떠요라고 할 때 비행기 날개를 단면으로 이렇게 딱 잘라보면 이렇게 되는게 아니라 요렇게 되 있어요 위에는 볼록하고 아래는 덜 볼록해 그러다 보면 공기를 가를 때 아까 똑같은 공기가 요렇게도 가서 만나고도 가서 만나겠지 그런데 위쪽은 더 길지 그러니까 근데 똑같이 만났는데 더 길면 더 빨랐지 여기는 빠른 공기야 여기긴 느린 공기고 그럼 빠른 공기 압력이 낫잖아 올라가는 거 그 둥 뜨는 거야 그렇게 설명 들었거든요 그래서 그렇게
(53:55) 얘기했더니 그 아니라고 아데 그 그것도 말은 되는 거 같은데 아 그게 그렇게 날개를 설계하면 다른 방식으로 설계한 것보다 비행기가 뜨는데 도움이 되는 건 맞죠 어 아 그러나 그러나 그게 가장 중요한 건 아니라 똑같이 이렇게 하더라도 뜬다이 거죠 심지어 비행기가 거꾸로도 나잖아요 아 그렇지 그렇게 하면 말이 안 되 예 그럼 말이 안 되는 거죠 압력이 반대로 되는데 아 그건 뒤집힌 거 아니야 그렇게 난은게 아니야 그 나이가 뒤집힌 거 아니냐고 그렇지 그렇지 그 뭐죠 그 그런 그 비행기 조종사들 하는 그런 데선 그런 묘기들 하잖아요 정말로 꼭 집어도 날수 있는 거니까 아 예 아 그래서 야 알겠습니다 헤어드라이기로 해도 이렇게 위로 뜬다 이거죠 옆으로 안 날아가고 안력 차이가 생기니까 헤어드라이기로 해 보시면은 그게 더 좋죠 이거는 뭘 사야 될 거 같은데 헤어긴 되게 다음 셀스 좋겠네요 그렇지 다이슨 같은 거 쓰면 뭐 꼭
(54:59) 다이슨이 써야 될까 싶긴 하 때 협찬 한번 받아보겠다 아이들한테 기왕이면 좋은 모습 보여 주시려면 다이슨 헤어드라이기 셉니다 아주 이런다고 협찬 않할 것 같습니다네 또요 또 그건 뭡니까 교수님 아이 이게 그 갈톤 보드라고 하는 갈톤 모드 예 장난감인데 장난감이라고 하기 좀 굉장히 이거 심오한음 보시면 이렇게 노란색 커브 보이시죠네 이게 어떤 확률 분포 같으세요 정규 분포 비슷한 거 어 얘가 여기 구슬이 작은 쇠 구슬들이 많이 모여 있고요 제가 이걸 뒤집어요 아 그럼 쇠구슬 쇠 구슬이 임의의 길을 선택해서지 여기 보시면 이렇게 오톨도톨한 이렇게 무슨 무늬 같은게 보이 작은 동그란 막대기들을 쭉 있어요 수님 그 비싸 보입니다 비싸 보여요 이것도 비싸 보여 몰래 근 기억을 못합니다 당근에서 수 왔어 당근에서 그래 이걸 뒤집으면 시작
(56:04) 여기 작은 구슬들이 오다가 그 짧은 막대에 부딪히면서 랜덤하게 왼쪽으로 가고 오른쪽으로 가고 됐 거 옛날에 무슨 그런 거 많았는데 뭐 이렇게 놓고 어느 선으로 가면 1번 하면 몇 점 뭐 뭐 어 사다리 타기 게임 같은 그런 거잖아요 렇게 되는지 궁금하다 구슬이 막 불러 내려오다가 거의 전기 분포에 맞는 모양을 만들어 아 예 와 저거는 되게 정교하게 저걸 했나 봐요 보통 저런 장난감은 한쪽으로 많이 가도록 뭐 그렇게 짜여져 있는게 많은데 이걸 갈톤 보드라고 부르는 이유가 이걸 처음에 그 제안한 사람이 갈 프란시스 갈톤이라는 학자요이 다윈의 외사촌 있가 아마 그렇고요 이분이 요즘은 우생학 자로 너무 유명하긴 한데이 통계학 분야에서도 꽤 큰 업적들이 많아요 예 그렇지 그 중간 값이라고 있잖아요 평균값 말고 중간값을 제한한 사람이이 사람 미 가운데 미디어 자 줄서서 무조건가 예 맞습니다 그거에 그걸 제하는 사람이
(57:07) 갈 상당히 유명한 사람이고 이분이 이제 정기 문빠가 만들어지는 아주 간단한 장치를 소개를 한 거죠 이게 꽤 중요해요 그래서 이게 그이 사실은 구슬 하나 하나는 왼쪽으로 갈지 오른쪽으로 갈지가 그때그때 결정되는 그거는 이항 분포고 보통 하거든 근데 굉장히 많은 구술이 있으면이 이항분포가 정규분포로 된다 예 정확히 큰수의 법칙이고 이게 그래서 통계학자들은최소한 하다 보면 한쪽으로 몰리는 경우도 없어요 그렇지는 않아요 무조건 이렇게 됩니까 꽤 많잖아요 큰수의 법칙인 큰수의 법칙이라 그래서 구슬이 상당히 많으면 벗어나는게 정말 힘들어요 동전을 천번 던졌는데 다 안면만 나올 수가 있어요 한 번 던질 때 안면 나올 수 있고 두 번 던질 때 안면 나올 수도 있는데 천번 던졌을 때 안면이 다 나올 수 있냐고요 나올 수도 있지 지금 제가 세보 그러네 그러네 저거를 어 그렇지 한 100만
(58:12) 번쯤 하면 그래 하다 보면 한쪽으로 쫙 이렇게 그렇게 되는 일도 있을 거 아닙니까 거의 안 돼요 지금 내가 세 보니까 내려오는 구슬이 여기 충돌하는 횟수가 12번이 그든 그러면 여기 여기 내려온 구슬이 맨 음 예에 쌓이면음 부딪칠 때마다 오른쪽으로 튕겨야 돼요 아 12번을 12번을 연속으로 오른쪽으로 가야 되는데 그 확률적으로 그럴 수 있겠냐 동전을 던져서 12번 내내 계속 안면이 나오는 거랑 똑같은 확률인 거죠 아 그럼 저 끝에 있는 조그만 애들은 그 12번의 확률을 뚫고 간 애들이네요 1분 1이죠 아 번이니까요 2에 12승네 오 1024 * 4면 오 오 대략 496 그렇죠 그니까 5,000 불레 엄청나게 확률 적이라서 그래요 근데 가운데 있는 애들은 뭐 이게 순서가 얼마든지 왔다 갔다 하는게 가능하잖아요 그래서 확률이 큰 거고요 그래서 정규 분포를 구슬로 눈으로 직접 확인할 수 있어서 제가 매년 수업할 때 사용하는 장난감입니다
(59:15) 그렇지 저게 진짜 한쪽으로 쫙 몰리는게 나오면 정말 재밌겠다 학생들은 저런 거 하나 사 가지고 예 부모님이 넌 왜 성적이 안 오르니 왜 옆집에는 등을 했는데 넌 못하니 그러면 엄마 이거 봐봐이 구슬이 열심히 노력하면 오른쪽 끝으로 갈 수 있겠어 자 다시 한번 해볼게 어 자 여기서 구슬이 노력한다는게 가능할까 12번 연속으로 정답을 다 맞춰줘야는데 그런 거지 아 아 이것도 제가 갖고 있는 재밌는 장난감인데네 제가 이거를 그 보여 드릴게요 예 제가 그거 뭐 위아래로 탁탁탁 내려오는 거 그런 거 아니데요 제가 내려서 영화라는 글자가 나오면 영화 보러 가고네 공부가 나오면 공부는 거 공 자 자잠 하나는 영화고 하나는 저거 저거 저거저거 무조건 영화가 나올 거 같은데 저거 영화 영화 영화 보러 갈게요 예
(1:00:21) 영화 보러 간다 어이 다시 해볼까요 다시다시 예 쟤 뭘까요 둘 다하라는 뜻일까요 간 맨 마지막에 한쪽으로 기울었네요 다시 아이고 바꾸 보셨나요 영화였어 또 영화였어요 무조건 영화로 나 거 아닙니까 혹시 저 약간 의심스러운데 아니 저거 어떻게 공부 어떻게 영화만 나오지 앞뒤로 무작위로 흘러야 되는 건데 왜 영화만 나와요 처음에 그렇게 생각했거든요 그래서 아 이게 면이 나올지 뒷면이 나올지가 랜덤하게 결정되겠지만 보세요 제가 영화를 시작했어요 얘가 이쪽으로 혀요 그럼 여기서 공부가 이렇게 되죠 예 처음에 얘가 그게 아니라 어 뒤쪽으로 해도 공부죠 그렇죠 예 아 두 번째는 공부 영화
(1:01:25) 공부 영화 공부가 가 반복해도 나올수 아 무조건 영화 공부해서 카니 메카니아 따라서 무조건 결정된다 그 얘가 이쪽으로 도나 이쪽으로 도나 상관없어 아카시아 가지고 나 좋아한다 싫어한다 좋아한다 싫어한다 좋아한다 저거 뜻 보면 이게 랜덤인 거 같잖아요 근데 생각해보고 이렇게 돌아서 그다음에이 떨어질 때도 공부고 뒤쪽으로도 들어도 공부 공부 상관없어요 기는 앞으로 갔다 뒤로 갔다는 하는데 그래서 그냥 약간 속임수 같은 형 아 아 그래 이거 하나 갖고 있다가 친구 오라고 해서 이렇게 네기 같은 거 하면 재밌겠다라는 저거 그러면 짝수로 해야 딱 맞는 겁니까 사다리 칸 몇 개 하 제가 그래서 영화가 나오게 하고 싶으면 그쪽으로 영화를 보여 주면서 시작하면 되거든요 무 좋은 지적이네요 여기서 하나 여기서 시작이니까 하나 둘 셋 넷 아에서 시 일곱 여덟 아홉 열네 맞네요 예 예 맞네요 그냥
(1:02:29) 짝수로 짝수로 하면 항상 똑 똑같은 결과가 나오는 거네 어 기 항상 똑 아 그까 왔다 갔다 하니까 결국 제자리로 돌아오는 거 홀 쓰면 반대로 나오는 거고 아 오늘 이걸 이렇게 내 기처럼 했으면 좋았겠다 제가 그죠 요거 갖고 와서 썸 타는 분하고 사귀는 거야 안 사다 안 사귄다 야 여기에 따라서 결정하는 거야 그렇지 야이 두 가지가 저는 꽤 재밌었어요 이거는 구슬 하나하나는 랜덤 하잖아요 근데 많은 구슬이 모여서 만들어내는 확률 분포는 아주 깨끗하게 정해진 모양이 나오는 거고요 이거는 랜덤하게 보이지만 사실은 정해져 있는 거죠 아 예 그래서 오늘 보여 드리려고 이렇게 갖고 와 봤습니다이야 저 구슬은 얼마 정도 해야 정규분포에 가까워질까요 구슬의 양이 적으면 딱 저 모양이 안 나올 거 아 이게 제가 어 그이 분포하고 정규분포를 비교를 하는 그림을 책에
(1:03:33) 넣었었다 해서는 안 나올 것 같은데 아 열 개만 해도 굉장히 정확해요 굉장히 그렇게 나와요 열 번만 해도 예 이거 생각보다 조금만 해도 굉장히 정확해요 어음 양옆으로는 안 갈 수도 있겠네 열 개 갖추면 열 개 하면 가운데로 가운데 개네 개 이렇게 있고 어 저 못 찾겠죠 그 사 봐야지만 알 수 있는네 알겠습니다 아이 자꾸 보니까 맨 뒷부분이 있네요 세개음 아 제가 아 좀 작아서 잘 안 보이시겠지만 커브가 세 개가 있잖아요 이게네 개 열 개 100 개예요 예 가만히 보시면 이게 그 점하고 선이 있는데요 점이이 구슬이 몇 개이라는 거고요요 선은 그거를 정규 분포 한 건데 100개 만 돼도 점하고 선이 구별이 안 될 정도고요 열 개만 돼도 거의 똑같아요 정도 아 열개만 돼도 생각보다 굉 정규 분포로 만 큰수의 법칙이 조금만 커져도 굉장히 정확해요
(1:04:39) 그렇죠 그래요 그래서 제가 가끔 이제 설명드리는 거 중에 한국 축가 축구 대표 팀하고 브라질 축구 대표 팀하고음 경기를 해서 누가 더 축구를 잘하는지 결정하려면음 브라질 축구팀 입장에서는 100 게임 하자 1천 게임 하자 해야 되고음 한국 축구팀 입장에서는 한만 하자고 해야 그냥 딱 단판으로 끝내 남자답게 그렇게 그렇지 그래야 이변도 나오고 아까도 봤잖아 그 의이 퍼져 있잖아요 근데 100 게임을 하면 어떻게 무조건 브라질이 브라질이이기는 거고 그렇긴 할 거 같아 맞습니다음 아 그래서 어 연애를 할 때도 아이 사귀고 싶은데라고 하면 오래 만나고 난 다음에 사귀자고 하면 안 돼요 아 두 번만에 사귀자고 해야 확률이 높아집니다 그냥 뭐래 만나면 내가 찌질하다는 걸 어떻게든 알게 돼 큰수의 법칙 와 많이 만나면 드러난다 어 어 그렇듯한 거 같습니다
(1:05:46) 그 어 나 오늘 한 얘기 중에 제일 설득 됐어이 얘기니까 와 알겠습니다 알겠습니다 뭐 하나 더 있는 거 아 하 좀 하나만 더 보여주 예 딱 하나만 더 보여 주십시오 하나네 아 아 이거 할까요 이거는 아마 보셨을 텐데 이렇게 손으로 이걸 잡고 있으면 얘가 위로 올라가서 막 끓는 거 같은데요 느낌이 예 어 어 뜨거 아 당신을 향한 나의 사랑이네 사실 이건 사실 별 건 아니고요네 밑 온도차 때문에 예 온도 때문에 여기 있는이 아랫 부분에도 사실이 바깥 부분에도 입자들이음 있잖아요 얘들이 압력이 커지고요 압력이 커지니까 아래에 있는 이걸 밀어내서 위로 올라가는 거죠 열 때문이 아니고 압력 때문이에요 아 그니까 열 때문에 압력이 커지는 거열 때문에 압력이 커지는 거고 근데 사실 제가이 PPT에는 그 그림을 넣었는데요 PPT 한번 보여 주죠 예예 PPT ES 오른쪽을 보면 이게 잘 보이실지 모르겠는데 위에는 색깔이 진한 녹색이고 아래쪽은 거의 투명한
(1:06:51) 액체 아아 그래서이요 지금이 장치를 이걸 그 증류기로 이용할 수도 있어요 아 제가 아 제 요거 좀 비춰 주시겠어요 이걸로 설명드릴게요 일단이 아래쪽에 모든 그이 액체가 모여 있잖아요 이거를 조심해서 예 해요 그럼 저쪽으로 흘러요 이렇게 하면 위에 고여 있고 밑에는 아무것도 없죠 그죠 왜 안 내려가죠 그 뚫려 있는 거 아니에 아 여기가 여기 막혀 있어요 막혀 있고 얘가 아래 이쪽으로 이동할 수 있는 건 안에 있는 관을 통해서요 아 예 예요 상태에서 위를 뜨겁게 하고 아래를 얼음 물에 넣 담아요 온도차를 많이 줘요네 그러면 어떤 일이 생 생기냐 men 위가 뜨거워지니 위에서 활발하게 움직이는 기체 분자들이요 관을 통해서 아래로 내려가는데요이 아래로 내려간 때는요 아래쪽에 얼음물에 요걸 담가 놓으면 거기가 차갑지아요 여기서 액체로 응결 돼요 그런데이 색소가 있는데 색선을
(1:07:58) 기화하는 기화하다 아요요 그렇죠 그래서 아래에 모이는 액체는 말간 투명한 알코올은 모이죠 아 그게 사실은 그 증류주 만드는게 정확히 그 방법이에요 아 그래서 이걸 갖고 증류주 증류를 어떻게 하는지도 설명할 수 있고 그 온도에 따라서 압력이 늘어나는 걸로 이게 이동하는 것도 설명하고 해서 이것도 제가 학생들에게 연력 수업하고 할 때 사용하는 장난감입니다 그게 연력 있니까 그게 그런게 예 온도 압력 부피 사이의 관계 같은 걸 그 공부하는게 연력 이죠 야씨 채팅창의 질문 중에 그 교수님 앞에 있는 아인슈타인 인형은 대체 뭐냐 아 이건 어떤 원리를 설명한다 보다 제가 좋아하는 거라 갖고 왔는데요네 사실 아 이것도 좀 재밌긴 하 우리가 LED 만 치잖아요 예 LED 장치들 비보 전기 에너지를 받아 서 그걸 빛으로 바꾸는 거고요 예 이건 빛을 받아 여기 보면 이렇게 빛이 빛을 이용 해서 그거를 전류를
(1:09:05) 형성하고 그걸 갖고 힘을 만들어서 까딱까딱 하게 하는 거라서 LED 장치를 정확히 거꾸로 한다고 생각해도 되죠 아 저게 LED 장치의 반대 방 반대인 거죠 예 사실 그 전기는 반대가 많아요 발전기를 거꾸로 한게 그 전동기 그 모터는 전기를 전를 운동해 바꾼 거고 그래서 똑같아요 구조도 똑같아요 LED 빛을 받아서 받아서 아니지 전기를 받아서 빛을내는 거고 저거는 빛을 받아서 전기를내는 거고 태양광 이니까 아 간단하군요네 그렇지음음 알겠습니다이야 진짜 점점 빠져드는 물리학의 세계 야 진짜 대단하십니다이 아직 선주는 없으시죠 아직은 없습니다 아 얼마나 좋을까 할아버지가 김범주 님 어 막 이어 가지고 막 물량 설명해죠 장난감
(1:10:08) 가지고 놓는데 와 저도 손주가 손주가 생기면 좀 더 사도 되지 않을까요 그죠 손주 손주한테 줘야 그렇 그럴 때는 또 이제 사모님도 허락하실 겁니다 지금은 내가 보기엔 혼날 것 같아 어 전반적으로 살짝은 비싸 보이기 저것도 뭐 그냥 제가 좋아하는 거랑 그냥 갖고 왔는데요 보니까 제가 보기엔 저 한 5만 원 나이야 알겠습니다 세상에 오 정말 재밌네요 물리학을 이용한 장난감음 요런 건 진짜 나중에 교수님은 만들어서 팔아도 잘 팔릴 것 같아 물리학 키트 장난감 키트 해가지고 파는 거지 이걸 어 아 저렇게 키트로 키트로 해서 만들어서 그렇지 아 김 장난감 저 하고 어 책하고 장난감 딱 히트로 해서 세트로 얼마 어 그렇지 저거 책만 봐서 어떻게 아이하고 놀겠어 그 그렇습니다 해볼까 우리 어 저희랑 전속 계약을 맺고 교수님 언더스탠딩 쇼핑몰에서 한번 팔아
(1:11:12) 보시죠 우리도 아예 그냥 먼저 선주문 받고 100명 모이면 100개 제작해서 거 보내 보내드리고 그렇지 그렇지 아이와 놀아주세요음 알겠습니다네 잘 될 거 같다고 예 아 진짜 재밌있는 물리학 기야기 야 물리가 이렇게 재밌는 줄 알았으면 저도 물리학과를 가는 건데 뭐 성적은 됐다는 뜻입니까 만만치 않아요 때는 물리학과가 되게 높았어 찮아요 옛날 그랬지 어 옛날에는 정말 물리학과가 천재들이 가는 그런데 그과 전국 수석은 이과는 물리학과 항상 그랬었지 그렇지 그렇지 야 훌륭한 과학자가 어 그렇 모든 아이들의 꿈이던 시절에 김범준 교수님은 그럴 때 물리학과 들어가셨어요 그렇죠 옛날이 물리학과 점수 높을 때 가신 거지 야 어때 좀 후회대 괜히 했어 AI 했었어야 되는 건데 그 제 그과 동기들끼리 하는 농담 중에 하나가 아 우리가 시험은 잘 봤는데 똑똑하진
(1:12:16) [웃음] 못했어 그 안는 있을 수 있 맙습니다 데 후회하 후회하진 않아요 그 물리학자로 살아가는게 어떤 과학자가 그 과학자란 인간의 가장 행복한 상태다 그런 얘기도 남긴 사람도 있거든요 그래서 그냥 행복하게 사는 거 얼마나 힘들었으면 그런 말까지 남겨 그랬을까 그게 제일 즐거 울리는 없 그거밖에 없 알겠습니다네 아 재밌게 잘 성관 대학교 물리학과 김범수님 고맙습니다 고맙습니다 [음악]