# Marshmallow Shooter Question

1. Jan 30, 2010

### scienceboy

Hi.

I might be too young for everyone, but I need help finding info for my science project.

I'm making marshmallow shooters out of pvc pipe and I am trying to test if turns in the pipe effect the distance the marshmallow goes. I made three shooters all the same length, one straight tube, one with 2 bends, and one with 4 bends.

Does anyone know where I can look on the internet to find info that would help explain the science behind this project? Or does anyone know? I need it for my paper that I have to write.

Remember, I am a little dude (10 yrs.).

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

2. Relevant equations

3. The attempt at a solution

2. Jan 30, 2010

### PhanthomJay

Scienceboy, welcome to PF!!
You're never too young (or too old) to seek help!
You might want to do a google search on 'Marshmallow Shooter Physics" for some guidance. I would think a straight shooter works best, because when a pipe curves, the marshmallow will be squished against the side of the pipe (like when you are riding in a car and the driver makes a sharp turn), causing a loss in its motion energy due to friction between the 'mallow' and pipe. Experimenting would be best.
A 'lil dude with a good question! Keep on asking!

3. Feb 1, 2010

### scienceboy

Thank you for you help.

I tried 5 different shooters. Three straight, 88cm, 44 cm and 22 cm. The longest went the farthest. Then I tried two more, one with 4 elbow turns, one with 2 elbow turns. They were 88 cm long - the total pipe length including the turns, not the length of the shooter.

Both of the shooters with the turns shot the marshmallows the longest. But the one with the 2 elbows was the best.

I found some stuff on the internet about laws of motion and force. But I can't explain why the marshmallow shooter with 2 elbows shot the furthest. I would think it would be the straight one or the one with 4 turns. Not the middle one. My mom tried to put a picture of my shooters in this, but not sure it will work.

Thanks

http:///Users/shawnswanson/Pictures/iPhoto[/URL] [Broken] Library/Originals/2010/Jan 31, 2010/GEDC0610.JPG[/PLAIN] [Broken]

Last edited by a moderator: May 4, 2017
4. Feb 1, 2010

### scienceboy

Try the picture again. If this doesn't work then I don't know how to load pictures.

http:///Users/shawnswanson/Pictures/iPhoto[/URL] [Broken] Library/Originals/2010/Jan 31, 2010/GEDC0610.JPG[/PLAIN] [Broken]

Last edited by a moderator: May 4, 2017
5. Feb 1, 2010

### PhanthomJay

We can't see your picture, did you try clicking on "Manage Attachments" under the "Additional Options" heading which appears at the bottom of the screen with your reply response (click on it before you post, and upload your picture. It may take awhile (several hours to a day or so) to get it approved by the moderators).
Bends not withstanding, you also will get greater distance by aiming the gun up at an angle, rather than level. If you aimed it straight up, the marshmallow would fall, back down on your head; if you aimed it level, it will hit the ground after travelling some short distance; if you aim it at an angle (ideally, without air resistance, at 45 degrees), it will reach its maximum range, all other factors being equal. With marshmallows, however, air resistance will be significant, so you have to experiment with the angle of attack. Also, a longer barrel of the gun might give a greater range, as long as you don't lose too much air pressure along the barrel as you blow into it. There are so many variables, that's why experimenting works best.

Last edited by a moderator: May 4, 2017
6. Feb 1, 2010

### pantaz

How are you pressurizing the shooters? Are you measuring the pressure?

7. Feb 1, 2010

### DaveC426913

The number of elbows in the pipe would only be a problem if the marshmallow had to pass any of the elbows.

i.e. the muzzle of the shooter - thr part that the marshmallow travels down, should be straight. The rest of the pipe behind the marshmallow is the compression chamber, and can have as many turns as you wish.

How do you pressurize the shooter? By hand? Like a trombone?

If so, the thing that will most dramatically affect how far your mallow shoots is not the length of the pipe but the length of the travel when firing. Squishing the shooter by 2 feet (2 feet of travel) will get a farther shot than squishing it one foot (one foot of travel).

Do all your designs have a similar travel?

8. Feb 1, 2010

### theRIAA

I'm pretty sure he sticks the marshmallow in the back end and blows in the tube. I'm also pretty sure we're going above his head.

Simply: each time you blow, you may blow harder or softer. You can do this without knowing depending on your mood, or how tired you are.

The shooter with the longest "Barrel" will go the furthest, but up to a point. If it's too long, your lungs will run out of air and the marshmallow will slow down in the barrel.

I would not count pipe before the bends as part of the barrel because the marshmallow has to stop at each bend.

Try a 66cm barrel and longer barrels as well (use straight couplings to combine your already cut barrels)

9. Feb 1, 2010

### scienceboy

Thanks everyone. My mom put the photos on Photobucket and put them in here for me. I hope they show up.

I laid each shooter flat on a stool so that they would all shoot level and from the same starting place. I used a vacum, stuck it in the pipe, and then turned it on for each shot. I wanted to try and get the blows to be the same. Is that what you mean by pressurizing?

I thought the straight one would shoot the marshmallows the furthest. I still don't get why the 2 bend shot further. And why won't the 4 bend shoot even further?

Hope the pictures help, if you see them. Thanks.

http://i748.photobucket.com/albums/xx126/wowsybowsy/GEDC0610.jpg

http://i748.photobucket.com/albums/xx126/wowsybowsy/GEDC0597.jpg

http://i748.photobucket.com/albums/xx126/wowsybowsy/GEDC0603.jpg

10. Feb 1, 2010

### theRIAA

wow way more scientific than I imagined. Nice job.

But ahh... The vacuum (in "blow" mode i assume) takes about a second to get up to speed. It's very possible the marshmallow in the straight tubes leave the tube before the vacuum is blowing as hard as it can! The fact that the tube with one bend stops the marshmallow temporarily allows the pressure to build up behind it and allows more time for the vacuum to speed up. Now the marshmallow is shot out of a relatively long 66cm barrel.

I have made a few potato guns that use pressurized air. The key to making a potato gun shoot far is a fast release valve. Many times before the valve is even a little bit open, the projectile has already left the barrel! I think the same thing is happening here except you don't have a tank of compressed air that you have to release quickly, but rather a fan that has to get up to speed.

Despite this fact I think your setup accurately (fairly) represents how a human would blow into the pipe and I don't think your setup is wrong. Just explain the bend slows down the marshmallow and allows time for the fan to speed up and pressure to build behind it so it has more pressure when it reaches the final barrel than the marshmallows in the straight tubes.

The shooter with 4 bends has a very short final barrel so it will obviously not be able to get the marshmallow up to speed at the end despite the high pressure.

11. Feb 1, 2010

### scienceboy

Do you think if I made the last piece on the 4 bend shooter the same length as the last piece on the 2 bend shooter then they would shoot about the same? Would it matter that the front part of the shooter is longer - on the 4 bend?

Your answer will help me explain my results. We are allowed to ask others for help as long as we give them credit in our paper. So I hope no one minds if I show my teacher your answers to my questions.

Thanks

12. Feb 1, 2010

### theRIAA

I do think they would shoot about the same but likely slightly differently. I'm going to guess the extra dead air space will matter less than the gain in air pressure build-up so it will go further.

It will create more dead airspace (more friction), but i don't think it will cause any noticeable change in marshmallow range.