Question

While travelling in a train, it appears that the trees near the track are moving whereas co-passengers appear to be stationary. Explain the reason.

Answer 1

Step1: Relative motion

1. Relative motion of any object is analysed with respect to reference point. If position of an object changes with respect to time and a reference point then the object is said to be in motion, whereas if the object remains at the same point with respect to the reference point then it is said to be at rest.
2. For example All passengers in a same train appear to posses zero velocity with respect one another. On other hand with respect to a passenger in a train, a person standing beside the track appears to be moving at a speed of the train in opposite direction.

Step2: Explanation

1. While travelling in a train, with respect to a passenger or an observer inside the train, position of trees is changing, hence it appears to be moving in opposite direction.
2. Position of a co-passenger does not change with respect to the passenger who is observing, because both are travelling in the same train and have fixed positions with respect to each other.