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LFS Physics Problems-Can you solve them?

Fri 30 Mar 2007, 18:39

axus

S2 licensed

Quote from vrt3 :y = -3*sin(t) + cos(t) + k1*e^(2*t) + k2*e^(-t)

with k1 and k2 the two integration constants. (No, I'm not that good at solving differential equations: I just typed it in into Maxima

). Now, I might be wrong but it looks to me like the only way to keep y finite is to lose the term with e^(2*t). Therefore k1 = 0.
Now I'll assume you meant 'y = 4 when t = 0' instead of 'x = 4 when t = 0' (since x is entirely irrelevant anyway). Substituting k1 = 0, y = 4 and t = 0:

4 = -3*sin(0) + cos(0) + k2*e^0

or

k2 = 4 + 3*sin(0) - cos(0) = 3

So:

y = -3*sin(t) + cos(t) + 3*e^(-t)

LFS Physics Problems-Can you solve them?

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Fri 30 Mar 2007, 16:42

axus

S2 licensed

The driver of an LX4 presses the throttle until 9000rpm is reached and quickly releases it. A particular point's y-coordinate on the exhaust vibrates in such a way that it satisfies the differential equation:

(d^2y/dt^2) - (dy/dt) - 2y = 10 sin t

Where t is in ms after the release of the throttle and y is mm relative to the rest position of the exhaust. Determine the solution for y which remains finite as t -> infinity given that x = 4 when t = 0.

TEST Patch V6 (now V9) compatible with V

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Wed 28 Mar 2007, 20:34

axus

S2 licensed

Have you guys maybe downloaded corrupt archives? Maybe try re-downloading? It worked fine here. Thanks again for the patch, Scawen

.

24Hours Kyoto Long Rev - FREE FOR ALL!

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Wed 28 Mar 2007, 20:32

axus

S2 licensed

I'd love to get an LX6 team together but this is right in the middle of my exams.

This is also the reason I've been putting off the LXCC season 2, it's my final year at school before university and I need to do well. My schedule is busier than I expected. At best, I do 2 hours of LFS a week, all dedicated to SARL.

InSim changes needed (bug fixes, new packets needed, etc)

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Mon 26 Mar 2007, 16:57

axus

S2 licensed

I know this would be way too much work (I think) for these patches but it would be nice if a live telemetry system could be coded, including the RAF data as well as tyre temps and whatever other information you feel is realistic to supply in real time. Combined with some way to change strategy from an external program, I imagine this will put big smiles on the enduro guys' faces.

As I say though this is more of a "one day when there's time to polish off things more" thing I think.

LFS 3D Race Watcher / Live for Skidmarks

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Mon 26 Mar 2007, 16:08

axus

S2 licensed

Nice, Becky!

Higher res. interior Road Cars

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Mon 26 Mar 2007, 07:28

axus

S2 licensed

Lovely, wow!

A humorous MSN text!

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Sat 24 Mar 2007, 06:57

axus

S2 licensed

Quote from Aquilifer :Example of 1st order differential equation could be xy'-2y=x^3*e^x. (where y' is dervative of y). See the difference - that is an equation (something equals something) not a formula, function etc. Now the task is to find some y(x) which fulfills the equation. The answer is pretty easy to see so I leave it out. Uhmm

y' - (2/x)y = x^2*e^x
let I be the integrating factor:
I = e^(integral (2/x dx))
I = e^(-2ln x)
I = x^-2

therefore,
x^-2 * y = integral(e^x dx)
y = x^2(e^x + c)

:headbang: But if that was easy to see (ie. you could write down the answer without calculation), respect

.

Last edited by axus, Sat 24 Mar 2007, 07:01.

A humorous MSN text!

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Sat 24 Mar 2007, 06:21

axus

S2 licensed

Argh, fine, it's me. Shrug

It's not a common expression at this end of the world, ok? :schwitz:And I'm not a native English spea... nevermind. I'll let you guys laugh at me all you want. It's not like you get many chances. Last night was an exception.

EDIT: BTW, Jakg, IGCSE Additional Mathematics (assuming that's what you mean) is not nearly 9/10 of the A-level Maths syllabus. I should know, Wink

I got my A* for Add Maths, and then still had to work my arse off to get an A in A-level. Basically all of the paper 3 stuff is untouched in Add Maths, as well as some of the paper 2 stuff.

I'm now doing A-level Further Mathematics and that's... pretty mad, but a lot of fun. Smile

I'm actually alone in the class because everyone else in the school is too chickenshit. I was busy on 2nd order linear differential equations last night:
(d^2x/dt^2) + (dx/dt) + 2x = e^((2-3i)t)
Solve for x. Big grin

(Which is fairly easy if you know what you're doing, DeKo - the d.e.'s in 3rd year uni or something are probably much much harder

)

Last edited by axus, Sat 24 Mar 2007, 08:46.

Which are the best servers???

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Fri 23 Mar 2007, 19:43

axus

S2 licensed

Wow. There's accepted etiquette (big word, do you know what that means?) when racing online. Some of that includes not deliberately cutting corners to gain an advantage on most servers. If the majority of racers don't think you drive appropriately on the server, they will normally ask you to change that. If that fails they may kick or ban you depending on the severity of what you're doing wrong. Sometimes this is just because the majority of the people on the server are idiots (ie. a bunch of people taking control of a server by banning everyone that joins) but seeing as I've never seen that in S2, and the fact that you have admitted you were cutting corners, I'm gonna go with the assumption that you were the problem. It's a fairly basic concept to grasp really.

People don't mind hard racing, going on the edge, wheel to wheel with someone, scrubbing a bit here and there, even the occasional spin and crash, it's all part of racing. The problem is when people deliberately go against racing etiquette. You can find out more about that here.

See, LFS is a hobby. People do it to have fun and as such when a bunch of people do it together, it's meant to be as much fun as possible for everyone. If you only think of yourself while driving, you're gonna run into problems. And contrary to what you may believe, following these rules makes it more fun for you also because it's more of a challenge. That's enough for now, I think.

By the way you seem to have mistakenly entered your year of birth as 1971 instead of 1991, please fix it. Thanks!

TEST Patch V3 (compatible with V)

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Fri 23 Mar 2007, 18:58

axus

S2 licensed

Hmmm, I'm not so sure anymore, it might have been using an older version of the setup for that track by mistake but letting the rear step out a lot feels weird.

TEST Patch V3 (compatible with V)

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Fri 23 Mar 2007, 18:35

axus

S2 licensed

Quote from geeman1 :My wild guess would be that the new sounds are causing that. You don't get the same audible cues so you miss the slides.

Been using Dave's sounds for a while, they're virtually the same.

Right now I would put £50 on it that there have been physics changes (possibly confined to single player). Any takers?

TEST Patch V3 (compatible with V)

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Fri 23 Mar 2007, 18:30

axus

S2 licensed

All settings are fine... from what I can see, unless something changes to another value when the patch is applied? And I'm fairly sure I haven't forgotten how to drive overnight and I can't catch one in ten slides.

I'm not one to normally scream "OMG, the patch has physics changes" but
considering the circumstances...

TEST Patch V3 (compatible with V)

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Fri 23 Mar 2007, 18:21

axus

S2 licensed

Scawen, have you maybe made an accidental change in physics?

Driving the LX4 feels very weird suddenly. Ie. I normally catch more than 90% of slides in it, and now I just can't catch most of them.

TEST Patch V3 (compatible with V)

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Fri 23 Mar 2007, 17:47

axus

S2 licensed

Actually got quite a good boost in FPS on some places of the track

so good work there but watching a replay that was recorded with V2, it went out of sync. I've attached that (please ignore my shocking tyre warming abilities, it goes OOS just by the pit entry).

On another note, the new dials look a lot less arcadey than before, when we have faces for them it will make a huge difference to interiors.

EDIT: The OOS only happens on SPRs from what I've tried so far. Some get it sooner, some later.

Last edited by axus, Fri 23 Mar 2007, 17:53.

Westhill 2.0 (high res)

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Fri 23 Mar 2007, 07:17

axus

S2 licensed

Nice work,

completes the deserted airfield look well.

Edited pics

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Thu 22 Mar 2007, 04:47

axus

S2 licensed

Quote from VALE 46 :Couple of pics...

The red FZR is one hell of a skin,

Multiplayer patch after V3

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Wed 21 Mar 2007, 18:14

axus

S2 licensed

Well, I'm sure holding my breath in hope for false starts, hopefully that'd not invalidate the replays. Better support for endurance racing would be nice too - ie. not the currently limited array of options for timed races. We'll just have to wait and see I guess.

Kyoto 2.0 (high res)

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Wed 21 Mar 2007, 12:17

axus

S2 licensed

Looking at the ads around the oval section, they do look very nice on their own but put next to one another, they sort of don't blend I think.

The best webcomic, ever.

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The best webcomic, ever.

Wed 21 Mar 2007, 10:48

axus

S2 licensed

Many of you have probably seen this already but for those not so fortunate:

http://www.xkcd.com

Here's my favourites so far.

diNOSaur - the legend

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Wed 21 Mar 2007, 10:37

axus

S2 licensed

Quote from N I K I :I don't understand what are you want to say! You are telling us this tread is crap?

Is that sarcasm?

j

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Wed 21 Mar 2007, 06:30

axus

S2 licensed

+1

Adjusting tire start temp

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Wed 21 Mar 2007, 05:53

axus

S2 licensed

Cold tyres are a part of racing - they make the first few laps interesting. We'll probably get the option of warmup laps at some point. There's no reason to have anything more.

How long will you play LFS?

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Tue 20 Mar 2007, 17:24

axus

S2 licensed

Quote from AndroidXP :Till I die. Or LFS dies. Whichever happens first.

Ditto.

Kyoto 2.0 (high res)

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Tue 20 Mar 2007, 10:16

axus

S2 licensed

Many thanks again!

These look absolutely fantastic. I think the Kyoto GP kerbs could use a few cracks in the paint and a bit more detail but apart from that, these could hardly be better!