1038: "Fountain"

[bhoot]

Title Text: "Implausible, did you say? Sorry, couldn't quite hear you from all the way up heeeeeeeeere!"
Well, looks like the site layout is still different...
Also, I feel like it should be beret guy doing this.

[sardia]

Alt text: Implausible, did you say? Sorry, couldn't quite hear you from all the way up heeeeeeeeere!

I wonder how fast the water would have to go if someone strapped you into a seat with an umbrella.

[sardia]

bah, I checked twice, and you still beat me.

[rhomboidal]

I don't know if it's physically plausible or not, but I do know I need more "FWOOP" and "Wheeeeee!" during my day.

[Djehutynakht]

You'd at the very least need a strong umbrella though... this seems like a job for "The unbreakable umbrella".

[Rhombix]

I'm surprised no-one's ever thought of this... seems quite simple if you think about it.

[K^2]

Fountain about 10m tall at v²=2gh, or about 17m/s out of what appears to be an aperture of roughly 10cm in diameter, or about 75cm². That's 167.5L/s flow, which if brought to a stop would generate 1500N of force. More than enough to lift an adult male, but not very high, as thrust will drop off quickly with altitude.

On the other hand, umbrella withstanding that much force I don't believe in.

[kleingordon]

I love the art in the first panel. I don't know much about drawing, but that seems like it's difficult to do well.

[bhoot]

Fountain about 10m tall at v²=2gh, or about 17m/s out of what appears to be an aperture of roughly 10cm in diameter, or about 75cm². That's 167.5L/s flow, which if brought to a stop would generate 1500N of force. More than enough to lift an adult male, but not very high, as thrust will drop off quickly with altitude.

On the other hand, umbrella withstanding that much force I don't believe in.

10 cm? Where are you getting that from? It's thicker than his head. (Also, he's a stick figure, so it doesn't take too much force to lift him )

[CatOfGrey]

(Also, he's a stick figure, so it doesn't take too much force to lift him )

Oh! Wait! Is this like freshman physics? Stick figures have no thickness, and are not impacted by friction, air resistance, or any other physical process that applies force that changes with velocity...

[Linux0s]

While the ascent is thrilling... the uncontrolled descent is even more thrilling.

[Quicksilver]

I'm sure people have thought of this, and on the off chance it actually worked, the fall would hurt.

[WolfieMario]

Fountain about 10m tall at v²=2gh, or about 17m/s out of what appears to be an aperture of roughly 10cm in diameter, or about 75cm². That's 167.5L/s flow, which if brought to a stop would generate 1500N of force. More than enough to lift an adult male, but not very high, as thrust will drop off quickly with altitude.

On the other hand, umbrella withstanding that much force I don't believe in.

10 cm? Where are you getting that from? It's thicker than his head. (Also, he's a stick figure, so it doesn't take too much force to lift him )

I think K^2 means the hole the water's coming from, which certainly is not thicker than his head. Did you think he meant the umbrella, or the jet of water?

Also, stacking the aperture in panel 3 sideways in MSPaint, I found K^2's approximation of 10cm would make the man about 95cm (or barely a meter) tall, which is very short assuming he's a teenager/adult (and also breaks K^2's approximation of fountain height). Approximating the man as 1.7m, the spout should be around 17.9cm in diameter. Also, under that approximation, the central fountain is about 9 meters tall (it's 5.3x the man's height in the first panel), so to K^2's credit, that was a good approximation.

At any rate, physics isn't my department (I'm not sure where patronizing measurements falls on the food-chain of overanalyzing a comic, but I guess that's my department ), so I'll leave that to whoever wants to recalculate the flow/force.

[Eutychus]

I think this would be a much better fountain to try the idea out with.

[Sarrin]

Ironically, this was recorded at Bumbershoot:
http://www.youtube.com/watch?v=J3Z6AWRzK84

[Eternal Density]

(Also, he's a stick figure, so it doesn't take too much force to lift him )

Oh! Wait! Is this like freshman physics? Stick figures have no thickness, and are not impacted by friction, air resistance, or any other physical process that applies force that changes with velocity...

Are you one of those cruel scientists who puts stickmen in a friction-less vacuum?

[Djehutynakht]

Or put on a thermal suit and stand over Ol' Faithful.

You'd need a strong umbrella though. This seems like a job for the unbreakable umbrella.

[Eternal Density]

I think this would be a much better fountain to try the idea out with.

That's a bit out of my way, so I'll make do with this one. I even have a spare umbrella for it...

[edit] Actually I'm not making do, cos mine's better

[Ideas sleep furiously.]

/Queue people getting umbrellas ripped out of their hands.

[Eternal Density]

/Queue people getting umbrellas ripped out of their hands.

A queue? I'd expect a stack... well actually more likely a heap.
(While 'queue' does almost fit here, 'cue' works much better.)

[K^2]

Approximating the man as 1.7m, the spout should be around 17.9cm in diameter.

Which would double thrust estimate. But compared to his head, the aperture is much smaller. So I kind of just eye-balled it at 10cm. Either way, the thrust is sufficient. You just need something sturdy enough to "grab" onto it. Also, you'd probably get thrown aside almost instantly, but it can still be fun.

[ijuin]

That must be a pretty touch umbrella to hold up under that kind of force. ^_^

[BlitzGirl]

I'm sure people have thought of this, and on the off chance it actually worked, the fall would hurt.

Not if you had Mary Poppins's umbrella...

[SpringLoaded12]

Video game physics is fun.

[GulliNL]

I love the art in the first panel. I don't know much about drawing, but that seems like it's difficult to do well.

It's not a well, it's a fountain

In the Netherlands some company came up with storm-umbrella's, capable of keeping their structural integrity in winds up to 120km/h or 75mph, maybe those will work?

[omegahunter]

Given the updraft on the Umbrella is 1500N and is unbreakable, the force I can exert in grip is 60-70N, unless there is a very high coefficient of friction, umbrella is going bye-bye!

[da Doctah]

Gene Kelly eat your heart out!

[Al-pocalypse]

Also, I feel like it should be beret guy doing this.

Ditto, seems like a white beret thing to do. Though, thinking about it, he's more likely to be up at the top already, standing in an upside down umbrella that is floating on nothing but the implausibility of the situation.

[MSTK]

(Also, he's a stick figure, so it doesn't take too much force to lift him )

Oh! Wait! Is this like freshman physics? Stick figures have no thickness, and are not impacted by friction, air resistance, or any other physical process that applies force that changes with velocity...

He should have air resistance, because he has a cross-sectional area (his head).

edit: oh, i just realized what you were talking about.

haha i feel dumb.

[Kibate]

Even if this would work, the water is only a few centimeters deep at the bottom, the fall would hurt like hell
This is, if he is not an egoshooter character

[nowhereman]

I would be lying if I said I had never thought about this. I have also thought about launching myself into buildings with slingshots and using bedsheets to glide out of windows. The physics of my head are wonderful and a bit reminiscent of cartoons.

[gargletheape]

Why does the stream of water stop from *under* the guy?

[bhoot]

Why does the stream of water stop from *under* the guy?

Haha, I thought that too at first glance. The water you see beneath him is the water that was pulled up when he was picked up by the fountain. The actual fountain is to his right just like in the previous panel.

[shashwat986]

(Also, he's a stick figure, so it doesn't take too much force to lift him )

Oh! Wait! Is this like freshman physics? Stick figures have no thickness, and are not impacted by friction, air resistance, or any other physical process that applies force that changes with velocity...

Not true: http://xkcd.com/669/

[RyanfaeScotland]

While the ascent is thrilling... the uncontrolled descent is even more thrilling.

I'm sure people have thought of this, and on the off chance it actually worked, the fall would hurt.

Obviously the umbrella doubles as a parachute on the way down.

[BAReFOOt]

So in conclusion:
1. The water would rip that umbrella a new one.
2. If the umbrella could stand it, it would be ripped right out of the guy’s hand.
3. If it wouldn’t be ripped out, it would break his arm. (1500N! That’s more than the biggest monster of a supercar on Top Gear!)
4. If he would have monster arms, a monster grip and a monster umbrella, he’d still break his neck after coming down. Since the umbrella is far too small.
But given a parachute in his backpack… that monster could actually make it. ^^

I think I’ll go with something ultra-lightweight but sturdy to sit in, with a bigger umbrella-like roof, and take that Geneva one in a nice deep lake. Add the parachute, and I’m good.

[Uzh]

I think I’ll go with something ultra-lightweight but sturdy to sit in, with a bigger umbrella-like roof, and take that Geneva one in a nice deep lake. Add the parachute, and I’m good.

Take the fountain in the Binnenalster http://en.wikipedia.org/wiki/Binnenalster - it's only 40 m high and that would do...

[Kit.]

Implausible. The torque is not accounted for.

[madjo]

I would be lying if I said I had never thought about this. I have also thought about launching myself into buildings with slingshots and using bedsheets to glide out of windows. The physics of my head are wonderful and a bit reminiscent of cartoons.

When you fall (in your mind) do you have time to hold up a sign that says "uh-oh"?

[OP Tipping]

You'd need a specially engineered brolly but apart from that it should be feasible.