A PASSENGER , SITTING INSIDE THE TRAIN, IS FACING IN THE DIRECTION OF MOTION OF THE TRAIN .HE TOSSES A COIN THAT FALLS AHEAD OF HIM .IT MEANS THE TRAIN IS IN UNIFORM MOTION ,SLOWING DOWN ,TAKING TURN OR SPEEDING UP ?
The train is slowing down.
If the train was in uniform motion, then the coin would continue moving with the same speed as the train, and both passenger and coin would move the same distance in the time interval it would take the coin to go up and down. The coin would fall right where the passenger is sitting. Also, all physical processes are the same in all systems that move uniformly - the passenger should not be able to tell whether the train is moving or standing still, if the motion is uniform.
However, if the train is slowing down, the coin, once free, will tend to continue going forward with the same speed is before. The passenger, in the meanwhile, will have slowed down. The passenger will therefore has traveled less distance than the coin, and the coin will fall ahead of him.
If this seems counterintuitive, consider the fact that when you are riding in a car, and a car suddenly slows down, you - and all objects in a car that are free to move - will fall forward. This happens because of inertia, the tendency of any massive object to resist the change in velocity. When the car slows down, its acceleration is in the direction opposite to the velocity of the car, resulting in decrease of speed. Everything in the car then tends to retain the original speed, and falls forward.