## Physics Examples/Help With Differentials

Sage
Posts: 1,066
Joined: 2004.07
Post: #1
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.
Moderator
Posts: 608
Joined: 2002.04
Post: #2
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.