nope. doing the stupid thing.... Saw it on the internet and me and my cooworkers wanted to duplicate it. So we did, at work!

Then the next logical step BIGER! So we used 5 galons. If you watch the second video the slot we used to drop the mentos let out way too much pressure. Look real close on the left side of the tube you can see a stream of coke flying out of the slot. Over 15 feet.

We are working on improving the design a little more for next weekend. reduce the hole to .25 inch add alittle more coke. Then the hard part is rigging a drop design for the mentos so they will spread when the drop. The more surface area the quicker it reacts.

So next weeks goal is 50+ feet.

My parts need to start to come in again. Starting to get stupid stir crazy.

 

Since the pic was so small, couldn't tell what was going into the menehune water bottle. If you make the hole .25 inches, how can you get the mentos into the bottle? Or did you mean .25 inches smaller?

 

Agent Smith here

 

Ok here's how it goes. The neck (big plastic tube) is filled with 10 rolls of mentos; by my count thats over 150 at 15 per roll.

The nozel is .5 inches wide so mentos will not fit through it. the nozel is neck is turned upside down and filled to the card line and the card inserted to keep them there. The neck is then inserted into the rubber coupler and tightly secured. at which point they will stay until the card is removed and they are allowed to fall in 1 big lump into the 5 gallons of coke.

This creats an instant decarbonation (foam) and the expansion and pressure forces the coke up the neck and out the nozel. The top of the water jug is 1.75 inches wide the coupeler reduces the area to 1.5 inches wide then the nozel reduces that further to .5 inches. so constant pressure of CO2 + reduction in volume = greater pressure at the nozzel. Expanding volume of coke + increased nozzel pressure = acceleration. this is due to the propencity of the constant pressure attempting to move the same capacity of coke (5 gallons) through a reduced container volume. Easy to calculate the pressure ratios. Basicly the area of the bottle proir to the reduction of surface area to the area of the opening of the nozel.

So the math water bottle area before reduction = roughly 254.5 insq
Area of the nozel = .79 insq
output pressure is 322.2 times greater at the tip than just prior to the reduction. this causes the coke to accelerate up and out.

I could get into the accual calculations of predicting the height of the geiser but that involves the finding out the pressure of the CO2 release, actual mass of the foamed coke, rate of expansion and acceleration, then 9.8 meter per second per second (gravitational pull on the column) wind direction and velocity, atmospheric density, humidity, temprature.

The atmospheric condition boils down to figuring out the coefficient of friction on the coloum. From there you basicly take the absolute velocity (acceleration of coke - gravity) calculate the inertia of the coke and degrade the acceleration with the coefficient of friction. When you reach 0 for acceleration, thats the terminal height of the coloum.

With a wag at the unknowns I predicted between 20 and 25 feet. But I would have been wrong due to the venting of pressure from the card slit.

With a .25 hole the pressure will be 652.5 times greater than the static pressure before the reduction. With no slit you are looking at between 50 and 60 feet possibly more depending on other factors like viscosity of the liquid. If the force of acceraration is greater that the viscocity holding the larger droplets it will start to seperate much sooner than the terminal height. Like an airbrush.

Physics it's what I do. You asked and I think I may have pounded your answer into the ground. But do you kinda understand more on how this works?

Side note: Of those who might scrutinize the math alittle more. Remeber the majority of the number used are aproximate. For more exact measurement you need to pop out the ole' physice books and refer to sections on the laws of fluid dynamics, gas expansion, projectiles, and I think a few others dealing with other varriables. So those 6th year physics majors out there hush yer mouths, sit back and just enjoy.

Edit: On these 2 test I was about 25 feet from the jug, the next runs may be filmed from the top of the house to get a good feal for the height.

 

Got it! LOL...
I'll keep watching for your next vid...

 

As you might notice verry few of my answers are short. Especially when you ask about a subject I know. Infact I think this is one of my shortest posts.

 

Yeah one of those days....

and check out this site.
http://www.collegehumor.com

 

http://www.ebaumsworld.com/videos/beatbox.html

 

so yeah I cam across this in Tokyo Tuesday in Lowrider Magazine on the way home. It shows drivers ed student watching a teddy bear about to shove a steering wheel in the back door of there divers ed instructor. And if you look they are excited about it, even the teacher!

EDIT: Those who will ask. The symbol on the girls head in the back ground is a student driver sticker they put on the cars of learners who have been driving for less than 18 months. They have got stickers for the old folks too. If you hit a vehicle with either of these 2 stickers you are automaticly %80 at fault.