Simulating dynamics (e.g., physical effects of inertia, forces, wind) on strands (e.g., hair) during computer based animation requires quick and accurate approximations of mathematical curves. Each strand is initially represented as a B-spline curve. Line segments approximating the curve are created by using affine combinations based on the curve's control vertices. Dynamics simulation is performed on the line segment approximation. Once an approximated strand is simulated, it is converted back into a B-spine curve representation for downstream processes, such as rendering. The rendering process displays the simulated strand to the animator.