When a train first starts going down the railroad, it is very difficult for it to get going. When it comes to a stop, it has a hard time slowing down. Why is this?

A train is a very big and heavy object, so the bigger the object is, the slower it will begin to move. With that said, bigger objects are also heavier and will move fast once going. Since the train is a huge and heavy object it will need longer time to slow down and come to a stop.