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Physics Advice

on 9/14/2013, 3:18 pm
I've been trying to wrap my head around how physics works and I end up constantly failing I am very disappoint 
People tell me,"When something or someone reaches its peak height it comes down faster than it went up."
Maybe I'm slow, but I just don't get it, like how many frames should be used or should I use Motion Tween (blue frames) instead of Classic.
(sorry I have no examples atm)
But here's a written example: Let's say I get a rock, I want that rock to go up and then fall down as normally as possible.
I try using tweens I can get it in the air but when it goes up and comes back down its all fucked up and strange.
Then I try FbF and since I have no idea if there's a order to this I merely do it at random. Shoot I expected a trial, error, then success but nope ORlly? 

If anyone can throw a little advice my way I'd be most grateful





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Re: Physics Advice

on 9/14/2013, 3:41 pm
If you're just throwing that rock up:
-the moment it's thrown the rock is at it's fastest (going upwards)
-when it goes up, the rock should start to slow down
-once the max height is reached, the rock should come to a complete stop
-the rock should then head downwards increasing in speed



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Re: Physics Advice

on 9/14/2013, 4:09 pm
just one thing, if you're using flash cs4 or higher, avoid the motion tween stuff and stick with the classic tweens (i think that's what you're talking about). they're over-complicated for no reason and i really never used them.

carry on
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Re: Physics Advice

on 9/14/2013, 7:32 pm
@Leo wrote:you're using flash cs4 or higher
Well you see there's your problem.

Anyway when dealing with gravity you have to remember that horizontal speed is constant and vertical speed changes acceleration. Flash normally won't let you ease motion on only one axis, so doing this can be quite difficult. The motion of an object when x is constant and y eases up and down is an arc. What I do is create a curve as a guide, animate the object frame by frame using the curve as a reference, then remove the curve. Before anyone suggests the motion guide layer, I would only suggest using Flash's motion guide layer for very specific tasks, and not for every single curved motion. Practice frame by frame until you need curve guides as little as possible.





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Re: Physics Advice

on 9/14/2013, 8:28 pm
Silveblaze wrote:People tell me,"When something or someone reaches its peak height it comes down faster than it went up."
Wait isn't that wrong? It should come down as fast as it came up


Last edited by Granadico on 9/14/2013, 9:00 pm; edited 1 time in total





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Re: Physics Advice

on 9/14/2013, 8:57 pm
@Granadico wrote:Wait isn't that wrong? It should come down as fast as it came up
Yup. Unless it passes the point where it started on the way down.



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Re: Physics Advice

on 9/14/2013, 9:02 pm
@BDB wrote:
@Granadico wrote:
Wait isn't that wrong? It should come down as fast as it came up
Yup. Unless it passes the point where it started on the way down.
Yeah that didn't make sense. I guess from an animation standpoint that'd be good for effect, but realistically it should fall at the same speed as it risen (besides wind resistance and what not)





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Re: Physics Advice

on 9/14/2013, 9:04 pm
Gravity is a fixed rate. The force at which something is thrown upwards is variable. Gravity doesn't affect the object harder because it was thrown harder, or softer because it was thrown softer, that doesn't make any sense.





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Re: Physics Advice

on 9/14/2013, 9:12 pm
@Mr Lange wrote:Gravity is a fixed rate. The force at which something is thrown upwards is variable. Gravity doesn't affect the object harder because it was thrown harder, or softer because it was thrown softer, that doesn't make any sense.
I know that i never said that, or at least i didn't mean to imply that. I was saying from an animation standpoint it might look better if something fell faster then it was risen, like if a character jumped really high then came rocketing down extremely fast.





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Re: Physics Advice

on 9/14/2013, 10:26 pm
Dang man trying to jot down notes on ya'll advice but you keep adding more!
Thanks for helping out though Surprised 





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Re: Physics Advice

on 9/14/2013, 10:35 pm
@Mr Lange wrote:Anyway when dealing with gravity you have to remember that horizontal speed is constant and vertical speed changes acceleration. Flash normally won't let you ease motion on only one axis, so doing this can be quite difficult. The motion of an object when x is constant and y eases up and down is an arc. What I do is create a curve as a guide, animate the object frame by frame using the curve as a reference, then remove the curve. Before anyone suggests the motion guide layer, I would only suggest using Flash's motion guide layer for very specific tasks, and not for every single curved motion. Practice frame by frame until you need curve guides as little as possible.
i used to tween one axis and do the other one fbf but it's a weird way to work i think
and yeah, i never used the guides that much because i didn't like the way they worked
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Re: Physics Advice

on 9/15/2013, 10:41 pm
@Mr Lange wrote:Gravity is a fixed rate.
well i mean sure
but the way gravity applies to an object isnt at a fixed rate





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Re: Physics Advice

on 9/15/2013, 11:16 pm
ʇɹɐɥbǝıs bןɯ wrote:
@Mr Lange wrote:Gravity is a fixed rate.
well i mean sure
but the way gravity applies to an object isnt at a fixed rate
In other words, acceleration is constant while velocity is not.
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Re: Physics Advice

on 9/15/2013, 11:20 pm
@Rapidfir3Pho3nix wrote:
ʇɹɐɥbǝıs bןɯ wrote:
@Mr Lange wrote:Gravity is a fixed rate.
well i mean sure
but the way gravity applies to an object isnt at a fixed rate
In other words, acceleration is constant while velocity is not.
acceleration is the difference between final velocy and initial velocity so omg wats ur point





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Re: Physics Advice

on 9/15/2013, 11:29 pm
I was just making your comment a bit less obscure.
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Re: Physics Advice

on 9/15/2013, 11:44 pm
ʇɹɐɥbǝıs bןɯ wrote:
@Mr Lange wrote:Gravity is a fixed rate.
well i mean sure
but the way gravity applies to an object isnt at a fixed rate
i literally cannot figure this out. it sounds like you're saying that gravity isn't always applying to the object then it does then doesn't then ???





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Re: Physics Advice

on 9/15/2013, 11:52 pm
Mr. Lange said that gravity is at a fixed rate. He was basically saying "well yeah the acceleration of gravity is a fixed rate but how that rate applies to your motion (velocity) is not fixed."

But it was obscure (hence why your confusion) which is why I said "In other words, acceleration is constant while velocity is not."
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Re: Physics Advice

on 9/16/2013, 1:00 am
Ever heard of terminal velocity?
Gravity will only bring something up to a max velocity. Once an object reaches a certain speed, there is no longer any acceleration.
Although you're all really bringing this up for no reason lol it should naturally be understood that gravity's acceleration is fixed and the speed of an object is not.





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Re: Physics Advice

on 9/16/2013, 1:33 am
@Mr Lange wrote:Ever heard of terminal velocity?
Gravity will only bring something up to a max velocity. Once an object reaches a certain speed, there is no longer any acceleration.
Although you're all really bringing this up for no reason lol it should naturally be understood that gravity's acceleration is fixed and the speed of an object is not.
Yes.
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Re: Physics Advice

on 9/16/2013, 8:38 pm
we should make a physics topic





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Re: Physics Advice

on 9/16/2013, 9:36 pm
@Granadico wrote:we should make a physics topic
I must agree with you sir, I'm learning so much thanks to you guys.
To bad I am grounded otherwise I could actually put your advice to work and show a demonstration if I've understood correctly. Again thanks.





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Re: Physics Advice

on 9/16/2013, 11:55 pm
Fuck that, I'm taking Physics for Engineers right now and I fucking hate it >_> Damn professor giving us 12 - 16 hours of work per week
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Re: Physics Advice

on 9/17/2013, 12:33 am
Don't hate the subject, hate the meaningless work.
A lot of people hate math simply because schools give you an absurd workload of petty tasks, assuming you won't understand any detail in the subject unless you've been given an inhuman amount of life sucking paperwork to do about it.





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Re: Physics Advice

on 9/17/2013, 12:40 am
yeah, math is hella useful
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Re: Physics Advice

on 9/17/2013, 12:50 am
Yeah, I understand. I actually have a passion for learning things about this world; however, I do NOT have a passion to do fucktons of work along with it. I mean, I understand I need to know my shit and I need to know how to do my shit, and tbh whenever it comes to computer programming/engineering I actually enjoy doing that work, but fuck this other work. It honestly wouldn't be THAT bad though if I didn't have 3 pre-class quizzes, 1 pre-lab quiz, 1 lab, 1 homework assignment, 1 quiz, a set of in-class question for every lecture (3 days a week), and 2 hour reading assignments due EVERY week, PLUS work from other classes.

I know I honestly shouldn't be complaining though when there are people with careers (sometimes multiple careers), but this is a ton of fucking work for one damn class.
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