Physics Examples/Help With Differentials

Nick

Sage

Posts: 1,066
Joined: 2004.07

Post: #1

Jan 14, 2006 — 05:07 PM

I found a website (http://www.myphysicslab.com) that shows examples of 2D physics systems for a number of objects like springs and rigid bodies. It also explains things with some equations.

I'm currently trying to reproduce the single spring in my program (just learning some physics) but I am a bit rusty on differentials. I took very little calculus so I'm not very good with figuring out some of the things.

When it says
x'' = -k/m*x - b/m*x'
is that the same as
a = -k/m*x - b/m*v?

If so could I handle the position as follows (I intialized x = 4 and v = 0)?

Code:

    float m = .5; //mass

    float R = 2.5; //length of spring at rest

    float k = 3; //spring stiffness

    float b = .1; //damping constant

    float a = -(k/m) * x - (b/m) * v;

    v += a;

    x += v;

Thanks for any help.

Josh

Moderator

Posts: 608
Joined: 2002.04

Post: #2

Jan 14, 2006 — 05:29 PM

Nick Wrote:When it says
x'' = -k/m*x - b/m*x'
is that the same as
a = -k/m*x - b/m*v?

If x is the position function then yes, x'' would be acceleration.

Possibly Related Threads...

Thread:		Author	Replies:	Views:	Last Post
	Porting examples from an introductory 3D book	crazy_ut2k4	4	2,802	Feb 16, 2007 08:04 AM Last Post: AnotherJake
	Bullet Physics Library / COLLADA physics viewer	erwincoumans	14	11,323	Aug 12, 2006 12:59 AM Last Post: Fenris
	NSAffineTransform Examples	dancedrummer	2	3,910	Jul 1, 2005 09:34 PM Last Post: dancedrummer