thats soo cool!!

what if you took straight sided ones and placed them in a regular what would happen?

where do i find the cups with straight sides?
p.s. u rock!!!!

We tried this with cups that had straight sides and discovered there was no lift! However, we still don't understand what is going on in the cups with slanted sides, but we feel that is the cause of this physics mystery.

Thanks

Dear Mr. Krampf,
Did you ever figure this out?
-Maggie 12

well i'll try that! but if you find out what it is i'll really like to know

Ryne

I had so many wonderful ideas "floating" around the room! I demonstrated the floating cups and then had them try as many different variations as they could think of. We had the inner cup floating out of the outer cup no matter what we did! A hole in the bottom, slit up the sides, every other slit cut out, all the slits shortened up to the rim! One student even cut a hole in the rim and the rim came out until it was too little to stay in the outer cup. Some students had more success than others. The smallest fifth grade girl was the first one to get her cup to float. Really fun and something I could afford to do with my students. Now how do I explain what happened? :)

Would it be okay with you if I linked to this page from my website? Just asking since some people don't allow linking to their sites if you don't take their permission.

I believe the principle you are experiencing is what is known as the Coanda effect,discovered by Henri Coandă in the early 1900's.He discovered that fluids in motion are attracted to and flow around curved surfaces which creates lift. I work in an R&Dlab where we developed material handling equipment to move various media with the generated lift. A simple demonstration is to take a screwdriver with a round handle, hold it by the blade in a vertical configuration- handle up blade down. Now shoot compressed air at the handle at an acute angle and the screw driver starts to spin and lift out of your hand and will float and spin like magic.By varying the angle you can speed it up or slow it down.

Try a continuous stream of air on your cups you may duplicate the above result.

how can that do that andv so many cups

This is a very interesting experiment, but what would happen if you took the top off the cone and the you blow into the side? That would be the thing that I will test.

I turned the 2 cups upside down. I held onto the bottom cut and blew. Sure enough, the top cup blew off.

I turned the 2 cups upside down. I held onto the bottom cut and blew. Sure enough, the top cup blew off.

that's cool but when you blow on some of the cups they lift just a little bit. Its that little lift that you talked about first and when the cup went sideways it was just taking the path of least resistance.
Parker

Maybe the airpressure dossn't go all the way to the backside of the bottom cup, only streams along the front, building a pressure along the sides and front of the mug, making the top mug "climb" up the bottom cup, I got no cups to make experiments but got the idea from when you removed the bottom of the cup and sliced the sides.

Wich means (if my theory works) allows you to remove the bottom and the backside of the bottom mug.

Awesome site by the way, thanks!

that was cool i think the air goes threw the sides

I tried cutting a slit down the side, and cutting off the top, and it worked with a slit, and with the top cut off. I used paper cups, because the plastic cups we had didn't work because of the rippled edges.

om nom nom

Your a true scienctist

Super awesome
Cool
In Everything you see
Experimental
Not hard
Cups floating :P
Erika!

I tried the experiment my self using the same cups that you used, only I cut a small hole on one side of the inside cup. I then blew on the same side as the hole, and the cup didn't move. I turned the cup around, and blew on the opposite side of the hole, and the cup flew right up!

I tried the experiment myself with the same cups that you used, but this time I cut a small hole on one side of the inside cup, then blew on the same side as the hole, and the cup didn't move. I then turned the cup around so that I was blowing on the opposite side of the hole, and it flew right up!

hey mr.krampfm my name is bobby horne and i did some testing of my own and found out what makes the cups lift what actually happens is the cups when u blow on them and what i found was it was friction between the cup and the wind thats beingblown into it pushs the cup to the side and then goes around the cups and creates lift if u want to email me bhorne@hom.rescare.com

Did you try putting 3 or 4 cups together?

We put 4 plastic cups together and blew on the side... They all jumped out!

We're having fun with this experiment!

Did you try using perfectly straight cups? My guess is that when you blow in between the cups the air bounces off the walls of the outer cup and back to the inner cup so some air escapes through the slits and some stays in the cup. The slanted cup on the inside makes it easier to force the cup upwards because the slant is pushed a little before the air slips past. This causes some lift. The rest of the lift occurs when the air hits the brim. That's why the the cup won't lift when the top is cut off. Here are a few tests for you to try: cut the brim off of both cups, get straight cups, and instead of cutting the bottom and the strips off of the outer cup, reverse it and do it to the inner cup, but not the outer cup.
Tobias,
11

what if you dut off the rim of the cups? Maybe the air is being trapped between the rims!

The shape of the cup is the answer. You are pushing the inner cup away from you by breathing on it. The cup is actually trying to escape horizontally, but it cannot. However, the wide mouth of the cup provides a way for the inner cup to escape your breath by riding upward (and ultimately away). That is the only way for it to go away from you - to go up.

I used scrap paper and scotch tape to make some custom-shaped objects to play with: a large cylindrical cup, a large (cylindrical) tube, a medium-sized conical cup, a small cylindrical cup, and a small (cylindrical) tube.

I got lift in these cases: "cylinder in cylinder", "upside-down cylinder in cylinder", "cylinder in cone", "upside-down cylinder in cone", "cone in cylinder", and "upside-down cone in cylinder". (However, for "cylinder in cylinder", "upside-down cylinder in cylinder", and "upside-down cone in cylinder", I only got lift if I ensured that there was room for air under the object before I began blowing. There's automatically air under the inner object in the "cylinder in cone" and "cone in cylinder" cases, so they were easier; but all objects seemed to hover equally well once they got going.) It felt like the lift might have been slightly stronger in the "upside-down cylinder in cylinder" case than in the others, but I'm not at all sure.

I got nothing in these cases: "tube in cylinder", "tube in cone", "tube in tube".

I got suction in these cases: "cylinder in tube", "upside-down cylinder in tube", "cone in tube", and "upside-down cone in tube". (At first I had trouble distinguishing the suction from simple gravity, but then I realized I could rotate the entire experiment. If I blow into the bottom of the tube instead of the top, the object experiences upward suction and rises, and if I turn the tube sideways--sideways like a flute, I mean, not sideways like a blowgun--the object gets propelled out the end I didn't blow into.)

I then cut some pieces off of my cone and my small cylindrical cup, to produce a conical tube with 1.5-inch diameter at the top and 0.5-inch diameter at the bottom and a cylindrical cup with 1.5-inch diameter and a 0.5-inch hole in the bottom. As far as I could tell, these two objects behaved identically to one another (except for the aforementioned fact that a right-side-up cone automatically has air under it so is easier to get started): I got lift in the "holey cylinder in cylinder", "conical tube in cylinder", and "upside-down conical tube in cylinder" cases, and suction in the "holey cylinder in tube", "conical tube in tube", and "upside-down conical tube in tube" cases. The lift was definitely weaker than it had been before (not surprisingly; you'd expect a cylindrical cup with a hole in it to have behavior intermediate between a cylindrical cup with no hole and a cylindrical tube); I think the suction was also weaker, but I'm not sure, especially with respect to the "upside-down conical tube in tube" case.

Finally, I tried setting a loose scrap (one of the pieces I'd cut from my cone) of slightly curled paper on top of the inner object. In the "tube in cylinder", "holey cylinder in cylinder", and "cylindrical tube in cylinder" cases, the scrap flew off. In the "tube in tube", "holey cylinder in tube" and "conical tube in tube" cases (holding the inner object to prevent it from falling through the tube), the scrap flattened itself against the object. (Well, sometimes it would fall off, but I think that was because of random drafts of air, shaky hands, etc., not due to air in the tube. I was happy to see it flattening itself even sometimes, since until then I hadn't been entirely certain that the "suction" effects weren't my imagination.) I wasn't able to use the scrap of paper on the "upside-down conical tube in cylinder" and "upside-down conical tube in tube" cases because it was too hard to keep my scrap of paper balanced on the narrow end of the tube while trying to find the correct angle at which to blow.

that was so COOL!!!!
i should try that!!!!

-Cathryne

Bernoulli's effect.

Hi,

I am by no means a scientist. I am an electronics technician. But I am a good problem solver. When I was watching this video, I thougt that if you could actually see where the air was going...then you could figure out what it was doing. I instantly thought of aero-dynamics tests that they do on experimental cars and airplanes.

I don't know if you smoke not(I recently quit so I'm not brave enough to try this myself)...but perhaps if someone were to take 1 clear plastic cup on the outside,and a solid color cup on the inside, and then inhaled a ciggarette and blew the smoke onto the cups then, you could see whats going on. What would even make it more conclusive is to take a high FPS camera and record the experiment...that way you could play it back in super slow motion to see exactly what the smoke did when it entered the crack between the cups. I bet you would be able to get a lot of interesting data that way.

Hope you get to try it soon!

Thanks,
Max (maxbrokeaway@hotmail.com)

What about the conical shape of the cups? What if you tried straight cylinders instead? Or if you keep the cones, what if you blow on the narrow end instead of the wide end?