A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, the second is full of assassins with loaded guns, and the third is full of lions that haven't eaten in 3 years. Which room is safest for him?
Answer:
The third room. Lions that haven't eaten in three years are dead.
In the back. See, the train is still accelerating as it is leaving the station so the train will be moving faster when the back of the train enters the tunnel.