The coin lands in your hand if the train maintains constant straight line motion. If the train slows down, the coin lands in front of you.
Work Step by Step
The coin is moving along with your hand and the train when you toss it. While in the air it maintains the same horizontal motion, so the coin lands in your hand. Please see Figure 2.19 on page 34 for a similar example of a coin tossed in an airplane. If the train slows while the coin is in the air, the coin will be moving faster than the train while it is in the air, so the coin will move forward relative to the train, and land in front of your hand.