Question

Two trains moving in the same direction with the same speed will be :

• A. At rest with respect to an observer standing outside the train.
• B. In motion with respect to an observer standing outside the train.
• C. In motion with respect to each other.
• D. At rest with respect to each other.

Answer 1

Answer: (B), (D)

At rest with respect to each other.

Rest and motion are relative, a body can be in motion with respect to an object and the same body can be at rest with respect to another object.
So if 2 trains are moving in the same direction with the same speed, and if two passengers, one in 1st train and another in 2nd train will look at each other, they will observe that they are at rest with respect to each other.
Whereas, for a person standing outside the train both of them will appear to be in motion.