How to determine projectile velocity with a phone book

[MRR]

A fellow YouTuber posted on one of my videos that he has build an air gun that is capable of 2000 fps. I told him that this figure is more than unlikely but he insisted on that number.

His calculations are like this....
300 fps pellet gun penetrates 9 pages
homemade gun penetrates 92 pages
= 10x as strong/fast

10 x 300 fps = 3000 fps (yes he even did the basic math wrong)



[youtube][/youtube]

Please don't troll this guy, this is just an example how not to do it.

PS.: about 15min of the 21min video is him counting pages

[wyz2285]

I have seen other fails, but not this level yet

[killerbanjo]

GAHHH MUST.... NOT.... TROLL.... URRR

[Crna Legija]

ahahaha lol does it work for golf ball cannons?

[Technician1002]

Have you sent him the link to GGDT?

[jackssmirkingrevenge]

Oh dear.



This is what happens when you let the marketing department sell on the basis of feet per second.

[pneumaticcannons]

thats pretty hilarious
But why was the video for "adults only"? maybe there was a porno scene at the end , I was too bored to watch the full video so I wouldn't know

[D_Hall]

Why can't we troll him?

Anyone THAT misguided NEEDS to be brought back to Earth. I mean, this is a harmless bit of stupidity, but what happens when his stupidity starts to wander into the realm of dangerous?

[wyz2285]

I´m sorry
I went to troll him, because I couldn´t stop laughing when he said:"if you are under 18, don´t make any questions, I will NOT answer you"
LMFAO

[MrCrowley]

i promise this gun is the best in the world, i made it and i know what i did to it, i discoverd something that you add to the barrel to double the speed, and by the i did not lie a bit about it, i believe my calculation is correct, air gun that shoots 300fps with the one i made very simple calculation, and dont be a fool like the other guy and tell i shot with a nail, i shot with same caliber as the marksman air gun its a BB

I'm with D_Hall on this one. Misinformation should be sought out and removed from the public sphere in this case.

[jackssmirkingrevenge]

Looking at his other videos, he might not be completely "there" so go easy with the trolling, just be polite and back your claims with data.

KE = 1/2 x m x v x v

It's kinetic energy that causes the penetration, not the velocity alone.

Assuming (tenuously...) a linear relationship between energy and penetration, and his creation is penetrating 10 times more that a 300 fps BB gun, then the KE is 10 times greater.

As mass is constant, we can say that v x v is 10 times bigger. Therefore to find the velocity, √(300 x 300 x 10) which gives us 948 fps.

[MrCrowley]

just be polite and back your claims with data.

KE = 1/2 x m x v x v

It's kinetic energy that causes the penetration, not the velocity alone.

Assuming (tenuously...) a linear relationship between energy and penetration, and his creation is penetrating 10 times more that a 300 fps BB gun, then the KE is 10 times greater.

That's more or less the route I took with him and I gave an estimate of 800fps+ but he still ignored me and wouldn't comment on the physics. He thinks his design is so brilliant he can ignore everything else.

No idea how he expects 200PSI of air to propel a projectile 2700fps.

Edit: Only having just realised where he is actually from, it probably wasn't a good idea for me to quote David Hume's famous "what is more likely..." remark in a comment reply to him.

[jackssmirkingrevenge]

wouldn't comment on the physics

I don't think physics means much to him:

[youtube][/youtube]

[MrCrowley]

Oh wow, he is special.

[SpudBlaster15]

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