Styrofoam Slide (May 2015)

I suppose it is vibration sound created by movement of the uneven surface of the cup which result in standing and conflicting waves at the surface. The Same effect would be seen if the cup is placed on a vibrating table and the frequency is varied.

I have noticed the same effect on a CNC router where the combining and opposing sounds created by the router and the independent X and Y steppers produce a resultant sound and varying patterns on a cup of coffee placed on the cutting table. Most noticeable when cutting curves or circles.

Resonant frequency.

http://science.wonderhowto.com/how-to/make-paper-plate-speaker-actually-works-for-under-1-0141522/

I get the same thing on my paper plate speakers....

Chinese have a 'dancing bowl' (or some other name) - when you rub your hands around the rim, the water can put on quite a spectacular performance.

Resonances, standing waves, etc etc -

Some tricks to it, tho -

In action....

https://www.youtube.com/watch?v=OPXiQpD6ucs

https://www.youtube.com/watch?v=ivYUb4ldlHs

From Wiki :- Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam currently made for thermal insulation and craft applications. It is owned and manufactured by The Dow Chemical Company.^[1]

In the United States and Canada, the word styrofoam incorrectly refers to expanded (not extruded) polystyrene foam, such as disposable coffee cups, coolers, or cushioning material in packaging, which is typically white and is made of expanded polystyrene beads.^[1] The term is used generically although it is a different material from the extruded polystyrene used for Styrofoam insulation. The Styrofoam brand polystyrene foam, which is used for craft applications, can be identified by its roughness and the fact that it "crunches" when cut. Additionally, it is moderately soluble in many organic solvents, cyanoacrylate, and the propellants and solvents of spray paint. Another tradename for polystyrene foam is thermacol, originated by BASF for expanded polystyrene.

Should we outside of the US work on the surface angle and properties of a White Polystyrene cup?

I have disposed of all my disposable polystyrene cups.

I take exception to this Wiki article as it is somewhat misleading.

1. Both Styrofoam® and polystyrene foam are the same thing. The ONLY difference is the process used to make the end product.

2. The correct term is pre-expanded polystyrene beads. Coffee cups are made by putting a predetermined quantity of pre-expanded beads in a mold and injecting steam to expand the beads into a single mass.

3. Many inexpensive, clear "plastic" boxes are injection molded polystyrene.

(C8H8) n

More specifically, I believe slip-stick provides the non-linear exciting force, and the bowl vibration is caused by the object's response to to that non-linear exciting force.

But, but, if you put slip-stick on a pig, it is still a pig, and the slip-stick is still a slide rule.

A agree that this is similar to the build-up of stresses in a fault zone, where during a seismic event, the stresses overcome the "stick" part, and undergo rapid "slip", and continues to do so, until a sufficient stress releiving motion has taken place.

In the styrofoam cup, the reason the droplets travel so high is that the wavelet amplitudes undergo constructive interference at the cup's center of mass, and project this pressure upwards.

Thanks; although I was hoping for a GA, I guess I should appreciate that someone knew what I was talking about.

Does the effect change using a short and wide cup versus a tall and narrow cup ? / Or a cup with a thick base or a thin base ? / Should the water be distilled or mineral water ?

Sounds like an excellent test for you to perform.

Let us know the results, with pictures.

I still cant post pictures yet, send me your email and I will send you the pics and we can share the credit for the experiment.

Doesn't the green camera at the top of the reply window work for you?

Try it with any .jpg picture.

I take a picture, save it to the gallery, or to several other " file " ( whatchamacallits, like drop box, is that a program or a software ?) . When i try to load a picture to cr4, I get a message something like " nicht versten" or I cant understand your jpg. picture so too bad sucker, I ain't uploading it no matter how many times you cuss me out.

Your pictures may be too big. You can just wait longer or resize them with windows picture manager and 'save as' etc.

Jim

When you first move the Styrofoam cup the water in side wants to remain where it is, the water then moves setting up a reactive force, this force resonates with the cups sides generating waves towards the centre that produces the droplets.

That explanation suggests that the same phenomena should occur even if the cup is made of something else, like paper or glass.

Yes it does? though I had not thought of it perhaps the hollow cavities in Styrofoam? have a effect on the production of the droplets?

Vibration is at resonant frequency setting up standing waves in the liquid.

BINGO!! Now all we need is a non-linear forcing function, like the wetted plastic cup being wiped across the glass, to produce that resonant forcing function.

The bottom of the cup does not set flat on table. It's is suspended above it. Styrofoam is flexible. Any vibrations will cause the bottom to flex up and down. Causing waves in the water up and down.

This is really an exciting thread (groan)

Del

Thanks for the help! ;-)

I cant seem to get the table to move at that speed and the cup just stays in one spot

Seriously, wouldn't the point on the cup at which you applied the force make difference?

If you apply the force on the side of the cup by whacking it with a baseball bat the contents really dance about

Del

Wood or aluminium?

Maybe this will help.

electrostatics, friction induced . Triboelectrification

Welcome.

It is not electrical.

Strictly mechanical.

Someone mentioned resonance.

Have you ever made a wine glass "sing" by rubbing a wet finger around its top rim?

If you like singing glasses, you are in good company. Ben Franklin like singing glasses enough to invent a musical instrument around the process, called the hydrocrystalophone, or the glass armonica.

.

https://youtu.be/eQemvyyJ--g

What is creating resonance? There is the first action of motion. Second there is the calorific value of heat due to the coefficient of friction, and also the resonance of the Styrofoam cup. So, a velocity has been stipulated, on a smooth wooden surface, so does the friction of Styrofoam in motion generates some heat? which affects the coefficient of friction? which affects the resonance of the cup, which affect the resonant motion of the liquid to produce droplets? YES?

the styrofoam cup swings (perhaps by resonance) by the resistance of the Wood surface

size of the styropor balls

Well sir, if someone were scooting yours across a wooden surface, you might make a vibration as well.

like chalk on teachers table!

G'day. I know zip about this question but wondered if there might be a static charge build up in the cup and polarize the water? like charges repel and shoot the water out of the cup.

Not even 2c worth I know, but I did say I knew nothing.

Rod

LOL!

"The answer to this challenge will be posted later this month, right here on CR4".

Where?

That is the ultimate question - anyone who answers that challenge should be awarded Swami guru, or Ramakrishna Swami guru.

That and what happened to "Caption this"? Although it may be just me that is banned, due to stupidity.

Thanks, SlamiSlami Baloney.

I don't think you have been banned, and certainly not for stupidity.

I could be banned for thinking that my wife has become more nagative, for various reasons.

Another challenge question without an answer. Maybe it should be required to provide the answer along with the question which would then be posted at the end of the month.

I found the answer, I think...