Quantity of waves over a dist calculated by Dist+Vol, negating Speed? Kill me..

Become a member of the CGSociety

Connect, Share, and Learn with our Large Growing CG Art Community. It's Free!

THREAD CLOSED
 
Thread Tools Search this Thread Display Modes
Old 01 January 2013   #1
Quantity of waves over a dist calculated by Dist+Vol, negating Speed? Kill me..

Ok, having a debate about a silly concept with waves, about time/distance/speed and the quantity of waves passing different points.

My friend thinks that further out at sea, waves can be passing a point at 5 waves per minute, while closer in shore, they can be passing at 6 waves per minute.
He believes that due to the volume of the waves increasing that the distance between the waves decreases, without their speed changing at all.
I've tried explaining that distance is a part of speed.. can someone please explain it, because I've been trying for nearly an hour now.

"You'll have more waves over the same distance without any changes in speed, because they'd all be travelling at the same speed because you're increasing the volume of the wave."



I know it seems hopeless, I've tried explaining to him that you cannot change the distance between anything without adjusting the speed..
He still thinks that the waves coming closer together by their outer edges coming closer due to the waves expanding without their speeds changing somehow puts more waves within a set distance, and that the centre-points of the waves are irrelevant to the equation because it being a fluid makes it somehow specially exempt from the laws of physics.

He also thinks that he even has a side of a debate to argue for..
If someone can just quickly reply even if just to say whose 'side' is correct here.. and yes, I know how silly it is to even ask that, and that it doesn't need confirming, but for his sake if you could lol (given him the link to this post).


Hell while we're here, I have another friend whose obsessed with movies and thinks that the digital aspect of them is the easiest work and the least important, and that the producers or big names claiming the titles do the most of and the hardest work while having more skill at physically creating movies than anyone working for them. If anyone wants to leave a message for that guy, this is also the place.

Problem is I have Aspergers, and no matter what I say in person, it's not enough. All I do is give out the facts, even stress them.. then I'm told I'm wrong and that's that. Could use some support. Thanks =)
__________________
 
Old 01 January 2013   #2
If this is about waves needed for a shot. Then they can be any number of waves at any time. :P

Seriously, you just have to drop that argument. Pick your battles. This one isn't worth it.

Films with digital effects take a lot of work because you need to bridge many of the things that are there now with things that will only be there later. There's a lot of preparation work, and the two phases can be up to 4 months apart. With a gap that big, if you get it wrong on the live set, then there's not a lot you can do 4 months later to go back in time and fix it.

So the amount of planning, calculation, technical preparation, and risk assessment in making a motion picture with computer effects is extremely high. Image clarity is also very high now with High-Definition and 4K formats - It is like playing the wrong key in an Orchestra performance - you will be found out.

Therefore, it is not easy.
__________________
"Your most creative work is pre-production, once the film is in production, demands on time force you to produce rather than create."
My ArtStation
 
Old 01 January 2013   #3
Sorry mate, you seem to have massively misinterpreted this post.

We're debating simple physics here, or more like I'm trying to explain to him, that consistent repeating waves, an indefinite cycle, if changing in frequency while moving inland, must be changing speed.
No new waves are formed, we're talking about starting and ending with the same number of waves during these scenarios.


If there are 5 waves over a distance of 50 metres, but later there are 10 waves over that distance, then the distance between them has decreased, meaning that the ones behind are moving faster than the ones in front in order to catch up, meaning all the waves are decelerating.
This is where my friend somehow believes that the volume of the waves increasing will separate them, WITHOUT THEIR SPEED CHANGING.
He believes that their distance apart can grow, without the speed being changed.

That is to say that he believes that he can adjust a variable of speed, without actually changing speed.

The purpose of this post, is, for his sake, to simply ask people to confirm or deny his theory.



Aside from that, it does happen that I have a client for whom I'm designing waves in Maya (from where the argument stemmed), who claims to believe that further out at sea, 5 waves pass per minute, but towards the shore, 6 waves pass per minute.

He fails to comprehend the fact that there is a set number of waves..
He thinks that speeding them up will make more waves per minute pass one point than the previous.
He does not understand that the waves consistently accelerating based on their distance from the shore will increase the gap between them in conjunction with the increase in speed and negate the difference between the quantity of waves passing a set point.

Anyhow, the full purpose of this post, is to simply ask for you to back me up on the obvious maths here, on the reality of physics, for those people to see, and to make my life easier.
 
Old 01 January 2013   #4
Originally Posted by dudeman38: If there are 5 waves over a distance of 50 metres, but later there are 10 waves over that distance, then the distance between them has decreased,

The distance between the waves will have decreased if they are different waves. The waves could be exactly the same distance between each other and just be travelling faster.

All wave surfers know that waves peak as they pass over shallow water. Really big waves will peak and break if they pass over a hump in the sea bottom. The waves dont travel faster they just seem to because there is more to look at, if all the waves were uniform over any area, which they are not.

What hard work is is relative. Trying to get a film financed seems to me to be extremely hard work and is a 24/7 job, while poring over frames and stitching stuff together as a vfx jock seems to me to be very hard work,... and can often be 24/7

If I put on a serious face then I hope people will believe me.
__________________
The terminal velocity of individual particles is directly related to pink rabbits on a bank holiday.
Characters, Games, Toys
 
Old 01 January 2013   #5
As far as I know the speed of propagation of a wave is dependant on the density of the medium so all that happens with a wave as it gets into shallow water is that the amplitude increases, minus drag, reflection and wind effects, but I could be wrong. Actually I checked on line, when the water depth gets to less than about half a wavelength the wave stars to slow down so you will get wave crowding, presumably from drag as it starts to transfer energy from an up and down displacement into an orbital energy before cresting and breaking.
__________________


Last edited by tonytrout : 01 January 2013 at 07:39 AM.
 
Old 01 January 2013   #6
Chiming in because water is kind of my thing. Trust me, I'm a pig marooned at sea!

http://en.wikipedia.org/wiki/Dispersion_(water_waves)

Quote: Surface gravity waves, moving under the forcing by gravity, propagate faster for increasing wavelength. For a given wavelength, gravity waves in deeper water have a larger phase speed than in shallower water. In contrast with this, capillary waves only forced by surface tension, propagate faster for shorter wavelengths.
Besides frequency dispersion, water waves also exhibit amplitude dispersion. This is a nonlinear effect, by which waves of larger amplitude have a different phase speed from small-amplitude waves.


In short, no waves are created or destroyed along their path. Bigger waves move faster than small waves, but if all waves have the same amplitude and wavelength, they will maintain the same relation to one another.

And it doesn't matter if the waves have a nonlinear rate of travel. Say you're on one end of a swimming pool making waves, and your friend is on the other counting them. He will never count a wave you didn't make, and the time intervals between the waves that reach him will be the same as the intervals when you made them at the other end of the pool.

Also, this:
http://www.youtube.com/watch?v=DovunOxlY1k

On the other hand, the customer is always right. Present them the facts, and if they want it anyway, bury your ego and do it
__________________
This should take less than a few minutes.

Last edited by noouch : 01 January 2013 at 03:55 PM.
 
Old 01 January 2013   #7
Originally Posted by noouch: In short, no waves are created or destroyed along their path. Bigger waves move faster than small waves, but if all waves have the same amplitude and wavelength, they will maintain the same relation to one another.

Phew, glad we got that sorted!
__________________
The terminal velocity of individual particles is directly related to pink rabbits on a bank holiday.
Characters, Games, Toys
 
Old 01 January 2013   #8
also in your explanation, remember:

wavelength X frequency = speed
 
Old 01 January 2013   #9
One wrinkle is that waves slow down as the water depth approaches the wave height. So large waves tend to pile up as they get near shore and the wavelength gets shorter. I'm not sure, but I think you might still get the same number of waves passing a point over an interval... they are just shorter and moving slower.
http://www.physicsforums.com/showthread.php?t=411310

Last edited by Duncan : 01 January 2013 at 11:46 PM.
 
Old 01 January 2013   #10
I'm only trying to debate the basic maths here, consider the waves to be uniform..
In essence, the maths would be identical to comparing rocks on conveyor belts of increasing speeds in place of waves..
Please confirm for my client, that the fact that one belt moving faster than the previous one would not increase the amount of rocks passing per minute over a set point from the faster one than on the previous one. Look at it logically, it's very simple. Forget all the dynamics of waves here, we're talking the basic maths, nothing more. Said dynamics of waves cannot change these basic laws of physics, only obstruct the point of the debate with useless words and vague speculation without contributing to the understanding of the ultimate truths of reality in question.

Also please confirm for my friend, that if the conveyor belts are a constant speed, if the rocks could grow as they went along it, that there would not somehow be more rocks present within a measured distance as a result of their growth (the concept of an increase in frequency created by an increase in volume).

If anyone else is going to go into detail, please no normal people, I'm getting sick of your misdirection, so please, only those with Aspergers or other logical minds reply further than
"Well obviously, you can't alter a part of the equation of speed without changing speed.. distance can't decrease between two objects without their speeds being different to each other, and if distance is decreased by deceleration, of-course the difference in speed and resulting distances between the objects in question do negate each other towards making it impossible for more of something to be passing per minute at one point than another, or we have discovered the secret of duplication."

Thank you.. and I don't care if the waves are breaking, about the depth of the water, nor anything about what causes any change in speed or frequency, I'm talking about the existence of said changes in speed or frequency, and the maths involved with them..
And what you're doing there, is like replying to my asking if 2+2=4, and saying things like putting a hat on one of the 2's or painting the + purple might give a different outcome, but not actually answering the bloody question.. you emotional people can be such a pain to communicate with sometimes. Is 2+2, a 4?
Please look at it that way and stop wasting my time. All I wanted was a simple confirmation of the simple maths, so I could hopefully regain an ounce of hope for mankind, but it seems that's too much to ask for..?

Last edited by dudeman38 : 01 January 2013 at 12:17 AM.
 
Old 01 January 2013   #11
Wink

Having surfed most of the beaches in the Sydney metro area I can tell you that waves are highly unpredictable and unstable, they are effected by far to many variables to mention and to define anything from one set of waves breaking to the next. Except going over the falls will hurt every time
 
Old 01 January 2013   #12
Ok, you see that? That's what I'm talking about. No more of that. I don't care if the 2 is pink with ribbons and wearing a bow tie, you add it to another 2, and you get 4. That's what we're doing. No more Bobs thanks...
 
Old 01 January 2013   #13
Originally Posted by dudeman38: a wall of text

1. Yes, the conveyor belt analogy works well enough for the sake of this argument, and you are right on both counts. For people who think less logically, it still may not be the best way to argue.



The crowding part in this case would be the rocks transitioning to the slower conveyor belt.

2. Chill out you giant spergball.
__________________
This should take less than a few minutes.
 
Old 01 January 2013   #14
You are forgetting the most important part of wave function in an ocean, the depth of the water in relation to the height of the wave.

This affects hight and speed, frequency can be compressed so yes it can increase.
__________________
-

Visual Engineering, Inc.
Creative Communication | Industry Consultation
 
Old 01 January 2013   #15
Is this the most stupid thread ever on here? This guy has to be trolling.
__________________

You can have your characters photoreal, fast or cheap. Pick two.
 
Thread Closed share thread



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
CGSociety
Society of Digital Artists
www.cgsociety.org

Powered by vBulletin
Copyright 2000 - 2006,
Jelsoft Enterprises Ltd.
Minimize Ads
Forum Jump
Miscellaneous

All times are GMT. The time now is 08:01 AM.


Powered by vBulletin
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.