Two vertical walls of infinite height have their bases elevated h = 3.40 m above the ground, and are separated by a distance d = 10.0 m. A mass on the ground directly under the left wall is fired towards the right wall at angle α above the horizontal with an initial speed u = 30 m s⁻¹. For the angles α₁ < α < α₂, the mass undergoes a maximal number of collisions with the walls before falling to the ground. Assume all collisions are perfectly elastic and ignore resistive forces. Find the ratio α₁/α₂.