Have you ever seen someone make smoke rings? They have the scientific
name vortices and are related to other vortices like the whirl pool in
your tub or sink and even tornados. They look neat and they have some
very interesting scientific properties, but since smoking is very bad
for you it seems impossible to make them. Here's a way to make smoke
rings without smoking.
What you need:
• Cardboard Box (shoe box or tissue box works well)
• Plastic wrap
• Baby powder or matches
1. Take a cardboard box (a shoe box or tissue box work well) that is open on one side only.
2. Cover the open side with some plastic wrap (like Saran wrap) and tape it on well.
3. On the opposite side of the box cut a round hole 3 or 4 inches across.
4. You now have your smoke-ring maker so it's time to
load it with smoke. This part can be dangerous so please ask an adult
to help. There are many ways to get "smoke" into your smoke-ring maker;
you can put a piece of "dry ice" into the machine (don't touch the dry
ice with your skin, it is very, very cold), you can use some baby
powder, if it is fine enough, or you can use smoke (but be careful that
you don't light your box on fire!). You don't need much smoke to make
5. Once your machine is loaded you are ready to start
experimenting. To make a smoke ring just tap the plastic covered side.
What would happen if the hole were square?
6. What happens when your smoke rings hit something
like a stick? Try making two smoke-ring machines and then try sending
the rings at each other. What happens when two smoke rings collide?
(It's hard to make them collide so you may have to work at it for a
7. Try different methods for making the rings easier
to see (like shining a flash light on them). Can you think of more
experiments for your smoke-ring machine?
What’s going on?
The smoke ring is another vortex, just like the one in the tornado
tube, except this time it has been bent into a donut shape called a
torus. The air on the outside is moving faster than the smoke, so holds
it in the ring shape.
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Wonders of Physics
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