Ask HN: Toolbox or library for simulating classical mechanics problems?

CRANK

I'm looking for a toolbox or library to simulate classical mechanics problems usually found in textbooks.I want to for example see the oscillations of a usual double pendulum problem with ability to plot angles and forces at arbitrary positions. Or physical parameters of "box on a cart with friction" problem or real-time animation of a N-body problem. It'd be nice if it also supports 3d.1- In summary, suppose someone wants to go through Landau-Lifshitz or Goldstein books and simulate the problems on his computer. What tools should he be looking for?2- What is the keyword I should be searching for? Rigid Body Solver? Physics Engine? Numerical solvers of Lagrange (or Hamilton?) differential equations formulations? or should I be looking for Finite Element Methods?3- It would be great if there is a MATLAB/python/C++ solution and not a full-blown software like COMSOLThanks(x-post from /r/physics)