A molecule in a gas container hits a horizontal wall with speed 200 m and angle 30° with the normal, and rebounds with the same speed. Is momentum conserved in the collision? Is the collision elastic or inelastic?
Yes, momentum remains conserved in the collision. To check whether the collision is elastic or inelastic, we consider the kinetic energy of the molecule.
We find that the initial kinetic energy is the same as final KE. of the molecule as u=v=200 m/s
i.e. thus the collision is elastic collision.