## Help! Physics Project: Smoke Waterfall

1. The problem statement, all variables and given/known data

I have a presentation on our physics class and I have decided to demonstrate the phenomenon of Smoke Waterfall inside an airtight container. I saw my friend do this tons of times. It's really amazing but how can I explain the physics behind this trick? In general knowledge hot air is supposed to go up right? why is it the smoke coming out of the cigarette butt settle at the bottom? Help pls!

here's a video.
Smoke Waterfall

2. Relevant equations

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3. The attempt at a solution

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 Recognitions: Gold Member Science Advisor Staff Emeritus How much air is there in the container to begin with? Where does that air go when the smoke comes in? If you really don't know the physics why would you choose it as a presentation in a class? Have you considered asking your friend?

 Quote by HallsofIvy How much air is there in the container to begin with? *Default value? just air...in an empty container...with a hole on the side where you can insert a rolled paper to burn. Where does that air go when the smoke comes in? *this is how i understand this: the lit end needs oxygen to burn. I don't know why the other end(w/c is inside the container) serves as an exit for the smoke from the lit end. maybe the lit end i blocked because it's burning that's why the smoke comes out of the other end? and to answer your question, i guess it goes the same with the lit end w/c is outside of the container. fire sucks the air inside the container out. If you really don't know the physics why would you choose it as a presentation in a class? Have you considered asking your friend? *Yes, I have. They agreed with my proposal so (this is a silly reason) we could have a reason to smoke inside the classroom.
I'd like to know what physical principal laws were shown in my proposed demonstration.
And I guess out of curiosity too, I just want to know how this works.