Author Topic: Math is difficult and my brain is soggy. (Read 679 times)

Xalos · January 28, 2014, 11:46:44 AM

Technically it's not soggy, just suspended in cerebrospinal fluid, but anyway.

So I'm working on a continuous physics engine and decided to adapt the continuous interest equation to friction - namely, A = Pe^rt.
This becomes, for a given starting speed S₀, coefficient of friction c, and time spent t: S_t = S₀e^ct.

Now I'm wondering how to get this equation in terms of distance travelled D_t, in the way that if I know V_t = t, then D_t = t². Does anyone know how to do this?

EDIT: Technically it's S_t = S₀e^-ct because the Coefficient of friction is always positive.

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Emo Freak · January 28, 2014, 11:51:56 AM

Never have I gotten a headache so quickly. I was going to attempt to assist but I simply haven't the brain power or will to assist. I support you though. :D

Ipquarx · January 28, 2014, 11:55:16 AM

Why on earth are you trying to apply the continuous interest equation to friction?

Xalos · January 28, 2014, 11:57:23 AM

Quote from: Ipquarx on January 28, 2014, 11:55:16 AM

Why on earth are you trying to apply the continuous interest equation to friction?

Because brain! ...no, actually I wanted to cause the speed of a moving object to drop faster when it's moving quickly than when it's moving slowly. Of the formulas I can remember on my own, this seemed like the best fit.

Gumba Jonny · January 28, 2014, 11:58:25 AM

i'm sorry to kind of sidetrack here but how does friction relate to logarithmic growth
does friction increase over time, affecting distance travelled?

Xalos · January 28, 2014, 12:00:15 PM

Quote from: Gumba Jonny on January 28, 2014, 11:58:25 AM

i'm sorry to kind of sidetrack here but how does friction relate to logarithmic growth
does friction increase over time, affecting distance travelled?

Friction is correlated to speed - the faster you go, the more friction encountered. (Up to a maximum but I'm ignoring that fact.)
So the friction is a DECAY of speed, so the speed decreases over time.

Coupon · January 28, 2014, 12:08:49 PM

Wow that was interesting, using PERT for friction. That's fun stuff.

Ipquarx · January 28, 2014, 12:11:14 PM

http://answers.yahoo.com/question/index?qid=20091120220731AAoVwtW

Xalos · January 28, 2014, 12:19:48 PM

Welp, no one is actually, you know, answering the question I asked, so I'm going to continue trying to figure it out alone. Good work team!