Question

A train is moving out of a railway station. Then the platform is at/in _______ with respect to the train.

Answer 1

1. Relative motion is the motion of an object with reference to another object.
2. When a train is moving, the platform is at rest but when seen from the inside the train the platform looks like it's moving because of the concept of relative motion and reference frame.

Therefore, A train is moving out of a railway station. Then the platform is in motion with respect to the train.