(Figure 5.196) shows an elevator cabin, which is moving downwards with constant acceleration `a` . A particle is projected from corner `A`, directly towards diagonally opposite corner `C`. Then prove that
(a) particle will hit `C` only when `a = g`.
(b) Particle will hit the wall `CD if a lt g`.
( c) Particle will hit the roof `BC if a gt g`.
.

Explanation

Superimpose an upward acceleration `a` on the system. The box becomes stationary. The particle has an upward acceleration `a` and a downward acceleration `g. If a = g`, the particle has no acceleration and will hit `C`. If `a gt g`, the particle has a net upward acceleration, and if `a lt g`, the particle has a net downward accleration.