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wwilliam54
 
Quote:
Originally Posted by boshi View Post
what rabble?

what's wrong with F = ma?

zomg I'm smarter than newton?

in a dynamic situation you don't use instantaneous quantities

so you use f=m(dv/dt)

edit: *fixed
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Old 01-15-2007, 08:58 PM wwilliam54 is offline  
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wwilliam54
 
Quote:
Originally Posted by JimmySal View Post
In statics, dynamics, the first 3 physics classes I took, and in Design of Machine Elements f was equal to ma

Not anymore though. System Dynamics, High Performance Vehicle Engineering, Vehicle Dynamics, Advanced Systems Modeling, and Modern Physics cured that.

now, F = d(m * v) / dt

lol

lol
no
I cant wait for modern physics this fall, I want to see all the cool shit these equations evolve into
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Old 01-15-2007, 08:59 PM wwilliam54 is offline  
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boshi
 
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Quote:
Originally Posted by Dumbfuck View Post
in a dynamic situation you don't use instantaneous quantities

so you use f=m(dv/da)

who said a was a scalar quantity?

seriously, F=ma is a general case, which is always true, I don't give a shit how you want to write it

dv/dt is just as instantaneous as a
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Old 01-15-2007, 09:00 PM I Am 'fullvietFX's Bitch is offline  
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#108  

wwilliam54
 
Quote:
Originally Posted by boshi View Post
who said a was a scalar quantity?

as you move down a hill, g(a) changes

edit: no really, f=ma is good enough for simple shit like this
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Old 01-15-2007, 09:01 PM wwilliam54 is offline  
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#109  

JimmySal
 
For example, if you wanted to do a system model for a top fuel dragster, you'd need the F = d(m * v) / dt formula.

Since the dragster burns a great deal of fuel as it completes the quarter mile, its mass and therefore momentum changes. Hence the complicated calc based formula.

Come on king of auto-x! This shit is important if you're gonna make it in racing!
Old 01-15-2007, 09:06 PM JimmySal is offline  
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wwilliam54
 
Quote:
Originally Posted by JimmySal View Post
For example, if you wanted to do a system model for a top fuel dragster, you'd need the F = d(m * v) / dt formula.

Since the dragster burns a great deal of fuel as it completes the quarter mile, its mass and therefore momentum changes. Hence the complicated calc based formula.

Come on king of auto-x! This shit is important if you're gonna make it in racing!

then you get into multivarible calc
YAY!!!!
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Old 01-15-2007, 09:10 PM wwilliam54 is offline  
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#111  

JimmySal
 
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then you get into multivarible calc
YAY!!!!

Multivariable is easy. You just model it as simultaneous differential equations and/or transfer functions.

I prefer transfer functions because I can plug them into simulink and make pretty graphs that tell me how much better my new prototypes handle than my old ones.
Old 01-15-2007, 09:12 PM JimmySal is offline  
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wwilliam54
 
Quote:
Originally Posted by JimmySal View Post
Multivariable is easy. You just model it as simultaneous differential equations and/or transfer functions.

I prefer transfer functions because I can plug them into simulink and make pretty graphs that tell me how much better my new prototypes handle than my old ones.

I prefer difeq, becuase that all I have an idea on how to do yet
soon, soooooooon

lol
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Old 01-15-2007, 09:15 PM wwilliam54 is offline  
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#113  

JimmySal
 
Transfer functions are easy. You set the differential equation equal to the system input, take the laplace transform of both sides and solve so that you get output/input on one side.

I like them so much because you turn differential equations into fairly simple algebraic equations. Mad easy.

(this is a kind of watered down description, but its basically how you do it)
Old 01-15-2007, 09:17 PM JimmySal is offline  
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wwilliam54
 
Quote:
Originally Posted by JimmySal View Post
Transfer functions are easy. You set the differential equation equal to the system input, take the laplace transform of both sides and solve so that you get output/input on one side.

I like them so much because you turn differential equations into fairly simple algebraic equations. Mad easy.

sound liek it would be better
cant wait to learn em
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Old 01-15-2007, 09:18 PM wwilliam54 is offline  
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#115  

JimmySal
 
Quote:
Originally Posted by Dumbfuck View Post
sound liek it would be better
cant wait to learn em

My system dynamics prof. wrote the flight control software for the F-14 F-16 and F-22. He also wrote software to make a trainer jet behave like any other airplane from these, to migs, to transports. Its pretty powerful stuff. My big advice to you would be pay attention when you learn diffeq and laplace. Also, learn some EE stuff, it comes in handy.
Old 01-15-2007, 09:20 PM JimmySal is offline  
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#116  

wwilliam54
 
Quote:
Originally Posted by JimmySal View Post
My system dynamics prof. wrote the flight control software for the F-14 F-16 and F-22. He also wrote software to make a trainer jet behave like any other airplane from these, to migs, to transports. Its pretty powerful stuff. My big advice to you would be pay attention when you learn diffeq and laplace. Also, learn some EE stuff, it comes in handy.

awesome
I wont be doing too much stuff like that
I'm a physics major, not enginerding

nucular > *
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Old 01-15-2007, 09:21 PM wwilliam54 is offline  
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#117  

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boshi
 
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Damn, you guys have a lot of fun patting eachother on the backs for your undergrad lower division physics and math classes. I'm doing the same shit right now.
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Old 01-15-2007, 09:37 PM I Am 'fullvietFX's Bitch is offline  
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#118  

wwilliam54
 
Quote:
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Damn, you guys have a lot of fun patting eachother on the backs for your undergrad lower division physics and math classes. I'm doing the same shit right now.

way to miss the j/k

no really, my reasoning outstrips my math knowledge, its a pain in the ass that I just decided to fix
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Old 01-15-2007, 09:38 PM wwilliam54 is offline  
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#119  

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boshi
 
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Quote:
Originally Posted by Dumbfuck View Post
way to miss the j/k

no really, my reasoning outstrips my math knowledge, its a pain in the ass that I just decided to fix

I see. I never argue that it is unimportant, I just think it's really funny when people try to drop terms to impress people.

Oh shits multivariable calculus! Diffeqs! O gnoes! Those are seriously hard courses, so advanced you have to wait until freshman year of your undergrad to take them.
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Old 01-15-2007, 09:44 PM I Am 'fullvietFX's Bitch is offline  
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