A particle is projected from a trolley car with a velocity v→. If the trolley car moves with an acceleration a→ towards right, which of the following remain unchanged relativeto both ground and trolley car?

Vertical component of projectile relative to trolleyvyT=vsin⁡θand vertical component of projectile relative to groundvyG=vsin⁡θVertical component is unchanged relative to trolley and ground. Now time of flight =2usin⁡θgTime offlight remains unchanged relative to trolley and grorHrd.Hence, right choice is (c).