A plumb bob is hung from the ceiling of a train compartment. If the train moves with an acceleration a along a straight horizontal track, the stirng suporting the bob makes an angle `tan^1 (a/g)` with the normkal to the ceiling. Suppose the train moves on an inclined straight track with uniform moves on aninclined straight track with uniform velocity. If the angle of incline is `tan^-1(a/g)`, the string again makes the same angle with the normal to the ceiling. Can a person sitting inside the compartment tell by lookign at the plumb line whether the train is accelerated on a horizontal straight track or it is going on an incline? If yes, how? If no, suggest a method to do so.