Six particles at the corners of a regular hexagon of side $a$ move at a constant speed $v$
120948
Time taken for collision
128537
Block on a block problem, with friction
152476
Unique Perpendicular Geodesic
136790
hard self collision: make particles occupy space
134362
Rotation of group of rigid motions of cube is isomorphic to $S_{4}$
13265
Volume of an n-simplex
38485
Rotate (group) objects outwards on spherical particle system?
7234
Generate $n$ randomly oriented non-intersecting cylinders with fixed radius and length
53499
Equilateral triangle inscribed in a triangle
118407
Birthday Problem applied to collisions
62698
Multiple colliding balls
98488
Wrapped hexagon topology
90626
Work in circular motions
157171
Gauss circle problem : a simple asymptotic estimation.
89865
Force on a test charge placed at the center of a 13-sided regular polygon?
149585
Game with 37 diagonally-oriented holes, 10 black pegs and 10 white pegs
14863
Escape velocity at an angle