I''am trying to make a simple rigid body simulator. Getting the the linear movement to work was easy using these equations from a high school physic book: newPosition=oldPosition+velocity*time+0.5*acceleration*time*time newVelocity=oldVelocity+acceleration*time position, velocity and acceleration are all 3D vectors so the equations work fine. However I can''t get the rotation to work using these equations from the same book: newRotation=oldRotation+angularVelocity*time+0.5*angularAcceleration*time*time newAngularVelocity=oldAngularVelocity+AngularAcceleration*time The rotation is a 3x3 matrix and angularVelocity and angularAcceleration are both 3d vectors, so that direction of the vector is the axis about witch the body is spinning and the lenght of the vector tells how fast the body is spinning.

Try reading this stuff:
http://www-2.cs.cmu.edu/afs/cs/user/baraff/www/pbm/pbm.html
http://www.d6.com/users/checker/dynamics.htm