I'm trying to write a small rigid-body physics program. I already have the linear forces part done, using Euler's method. This makes it easy to take the current forces and compute the next position. The issue I'm having is that I don't know how to get the next angular position/velocity from the current torques on the body. If I use quaternions for torque, velocity and orientation, do I just left-multiply my torque rotation quaternions together, then use that to rotate my velocity, then use that to rotate my position?