Simple video on How Jellyfish Sting

[royaladam]

I heard it feels good when you get sting

[825DoubleC]

@Teghead Well said. A minor correction on your calculation though: sqrt(2ad) gives the final velocity, Vf, not the average velocity. The average velocity for constant acceleration over displacement d would be (Vi + Vf)/2 = 7m/s in this case (for Vi = 0), assuming the spine doesnt deccelerate in this regime

[Teghead]

And this factor of 100 means that the acceleration is 1 000 000 * g

rather than 10 000 * g

even more impressive! (You'd faint if you travelled at 6 * g )

[rob8675309ain]

A jellyfish isn't the only sea creature that stings.

[Queenapolooza]

omygosh! Harpoon like structures look scary!



[MultiDudes45]

very informational thank you for making this vid i wrote a whole page chock full of info from this video

[RacheeROFL]

I want a jellyfish to sting my nipple before I die.

[raycee123]

y am i here

[outwithlunch]

I watch this stoned ass, it is really trippy like that!

[outwithlunch]

Who Disliked? Who is it! Show ya self!

[0moaz0]

These things are out of space i don't know why they call it fish.

[godsentroyal]

Darnit nature you sure are frighteneing!

[punchmaster123]

You can actually feel all those little harpoon things going inside your skin for a very short amount of time (like a tenth of a second) and then right after that is when it hurts. I've been stung a lot...

[SOF006]

Ewwwwwwwwwww. I became all tingly after watching this... My fault I guess.

[therealKINDLE]

Ha ha! It's Dr Who's Son Sean Pertwee Narrating! Dr Who knows everything!

[Edub1321]

I just got stung by a jellyfish yesterday...

[GeoVII]

Apparently science has also revealed that firing nematocysts scream like Godzilla when they fire.

[LovedWife1]

What moron disliked this video?

[missfuzzy97]

In all these types of videos the voice of the man is so weird.

[Wolfboy183]

10,000x the force of gravity- what is that in miles per hour?

[Gonzaga78]

@Wolfboy183

the force of gravity isn't a speed unit

[outwithlunch]

@Wolfboy183  about 3x speed of sound

[Wolfboy183]

@outwithlunch 768 mph / 1236 km/h? A nematocysts fires with that much speed?

[KarelYalek]

@outwithlunch

10 000xG means pressure that each sting put on flesh. SInce the diameter is small even small force means big pressure. sry for bad english

[kathillina]

@outwithlunch erm how can force be converted into speed?

[outwithlunch]

@kathillina google it

[Teghead]

@kathillina

The narrator is mistakenly calling an acceleration a force. g = 9.8m/s*s

Therefore it's implied that the spine accelerates at 98km/s*s

(Meaning, if the spine begins stationary, after 1 s it would travel at 98km/s)

We aren't told how long the movement takes, but we could assume that the distance it travels is something like 1mm.

Then, average velocity=sqrt(2ad) = 14m/s in this case << speed of sound which is 340m/s lol

[kathillina]

@Teghead That's a good explaination. Thumb up ;-)

[Teghead]

@kathillina and 1mm/14m/s = 71microseconds the time taken to extend a spine.

If this seems like too small a prediction, then either the distance it moves is farther than 1mm, or the average velocity is lower than 14m/s.

I.e. 14m/s is a generous estimate so I think @outwithlunch is basically making stuff up!

[carlosmj38]

@kathillina f=m·a -> force causes an acceleration and that causes speed to a mass.

[kathillina]

@carlosmj38 what is "speed to a mass"?

[carlosmj38]

@kathillina produce an acceleration to a mass, with the acceleration you get an increasing speed

[kathillina]

@carlosmj38 From "speed to a mass" to "acceleration to a mass"? What is mass has to do with anything at all?

[carlosmj38]

@kathillina how old are you? you will see it in physics in high school ;)

[kathillina]

@carlosmj38 You didn't asnwer my question and went straight to insult me?

[carlosmj38]

@kathillina I don't see the insult anywhere.. why are you so difficult?

[carlosmj38]

@kathillina I just wnated to help you, I don't know why are you so agressive. The age is important because maybe you haven't go to high school yet and you will learned it. If you have go and you didn't learn physics, there is no motive to be upset, you can always study it by your own. I'm not a physist*, I'm studing biology, but I know that the thing that moves has a mass, for example the nematocyst of the video, unless you go to quantum physics, thats a whole diferent world :P.

[kathillina]

@carlosmj38 See the reason why I take it offended is because you assumed that I haven't been to high school. I'm well over the high school age where you just said that I have not been to high school. Not everyone in high school takes physics.

I'm merely just asking question. I want to clearify what you are saying. I'm not trying to be agresssive, only because you just assumed that I'm not educated as what you are trying to implying with your underlying message.

[kathillina]

@carlosmj38 Quantum physics has nothing to do with the simple classical calculations. Not only "the thing that moves has mass", everything has mass.

Teghead clearify it by saying that the author was trying to say acceleration instead of force, and provided answer to the questions. Newton 2nd law is to calculate the Force, not speed. With acceleration you get increased in velocity, no mass involved. Your posts "to a mass" makes no sense at all.

[carlosmj38]

@kathillina ok, I don't want to get into quantum physics because I will say nothing right, but you can't say everything has mass, for example photons and stuff like that has no mass and travels at speed light.

I only respond you to your question "how can force be converted into speed?" and I just so you the simple relation f=m·a, where you get the speed, maybe I was mistaken with the english, its not my native language....

[kathillina]

@carlosmj38 You are talking about invariant mass. If you're saying photon has zero mass than according to Einstein's equation, it has no energy. Now we know that is wrong, otherwise solar cells wouldn't work and photosynthesis will not take place. This is steering away from the topic.

[carlosmj38]

@kathillina yeah, thats steering away form the topic, I don't know why you say that and not answer my last comment. But its alright, if you don't want to tell there is no problem. I think you just need to study more, and not via youtube, thats my advice :D

enjoy life in general!

[kathillina]

@carlosmj38 Can you please tell me what was your last comment that you want my answer?

If its regarding to age, its personal and I can refused to answer.

Yet again you make another unwise assumption.

I don't really know why I bother asking.

[carlosmj38]

@kathillina ok, I think i've been really reasonable with you, and just trying to help, and all you want to do is argue and you take all my word wrong... so i'm going to finish this conversation in the inmature way... FUCK YOU :D

[kathillina]

@carlosmj38 Your 1st and 2nd comment already said you have no idea what you are talking about. You 3rd reply implies that I'm uneducated. Your following replies never really answer my question of what mass has to do with velocity. It is not about argueing, its about justifying your answer in a clear concise matter. You kept asking my age which has nothing to do with this subject. Your last two comments prove that you do imply that I'm uneducated and I study via youtube.

[carlosmj38]

@kathillina ....You shouldn't be offended at all, maybe I was mistaken to think everyone has a basic physics education, and I learned that thats not true, sorry for insulting and offending you. Other thing I've learned is that I will never answer to a simple question in youtube because all I say will be misunderstood... and by the way, "a force is that which can cause an object with mass to change its velocity" (wikipedia)

[kathillina]

@carlosmj38 Best to not assume at all. And you don't know if I have studied physics or not.

Yes force will change and object velocity with mass. But "to a mass" makes not sense. Teghead has already explained it very well.

[carlosmj38]

@kathillina ok, sorry to try to explain you anything, sorry for my bad english, and sorry for not knowing anything about your life. Maybe I would know you have studied physics if you have answered my questions... could you at least give me your age? it would make more sense

[Teghead]

@kathillina

Hey, you are right to be annoyed at all the bad explanations people are giving here. You are confused because these people are not being clear, not because you are stupid.

Speed (or velocity) is a change in position over time. v=Δd/Δt

Acceleration is a change in speed (or velocity) over time a=Δv/Δt

A force is a mass multiplied by an acceleration. f=m·a

You can also think of force as a change in momentum.

Momentum is speed times mass p=m·v

Then force is Δp/Δt

[Teghead]

@kathillina

The mass usually doesn't change for normal things, so Δp/Δt becomes m·Δv/Δt which is the same as f=m·a

If the mass did change in some strange case, then f=Δm·Δv/Δt

So you can see that forces change the speed of an object. If no forces act on a ball, it will travel at a constant speed in a straight line. Maybe the speed is 0 and it's not moving; there is no difference between rest and constant speed, velocity is relative to the reference frame, is the ball moving or are you?

[kathillina]

@Teghead yeah I know. Einstein's theory right?

[Teghead]

@kathillina

I think it was Gallileo's principle that uniform motion is relative, no reference frame is special. Einstein took it further to say that all the laws of physics look the same, for any 'intertial' (uniform velocity) reference frame. E.g. two observers travelling at different velocities relative to each other would both measure the speed of light as c. I still don't really understand what that means.

Einstein also showed a gravitational field is equivalent to a uniform acceleration.

[kathillina]

@Teghead I studied this and I forgot all about it. I don't really want to go into this because it has nothing to do with jelly fish :D

[Teghead]

@kathillina

And having mass in the equation for force should make sense: if you have 2 balls; ball1 has a mass of 1kg; ball2 has a mass of 100kg.

You put them both on a flat surface with no friction.

They start at rest (v=0) and you apply 1 newton of force to each for 1 second. Ball1 accelerates to 1m/s. Ball 2 accelerates to 0.01m/s

So mass is not really how heavy something is, mass is how much an object resists having its speed changed.

More mass gives greater impact at the same speed.

[kathillina]

@Teghead Yes yes, for calculating FORCE. Conservation of momentum.

[SlipstreamWarbird]

Damn nature. You scary!

[dlindeman]

Excellent animation

[NeonFoxLetsPlays]

i've been stung too. oh my god that was PAINFUL.