How is it possible to detect the approaching of a distant train by placing the ear very close to the railway line ?

(True/False): It is possible to detect the approaching of a distant train by placing the ear very close to the railway line.

It is possible to detect a distant train, which still can't be heard, approaching us by placing our ear very near to the railway line. How this works ?

Lenses Placed Very Close To Each Other

Would it be possible to detect on Earth sounds produced on another planet if you had a dector sensitive enough to very low intensity sounds ?

A train, travelling at 20 km//hr is approaching a platform. A bird is sitting on a pole on the platform. When the train is at a distance of 2 km from pole, breakes are applied which produce auniform deceleration in it. At that instant the bird flies towards the train at 60 km//hr and after touching the nearest point on the train flies back to the pole and then flies towards the train and continues repeating itself. Calculate how much distance will the bird have flown before the train stops?

There are 15 stations on a certain railway line. How many different types of tickets must be printed so that a passenger can travel from any station to another in that line?