A fully coloured model of Orbiting Billiard Balls (Nrich 4798).
This worksheet shows a billiard ball (E) on a table. [b]1) At what angle must the billiard ball be struck for it to return to its start position?[/b] Use point "F" to adjust the angle that the ball (E) is struck. [b]2) Your answer will depend on the length and breadth of the table, but does it depend on where the ball is to start with?[/b] Don't be too quick to accept this diagram - what assumptions might it be useful to make about the rebound angles?