While teaching relative motion, my 11th grade physics teacher had asked us this question:
“If a munnkey [sic] is running on a train, and the speed of train is 60 km/h. The speed of munkey is 25 km/h. Another train crosses this train in opposite direction at a speed of 70 km/h. What is the relative speed of the other train to this running munnkey?”
We probably solved it that day, but now when I look back, I feel that the solution that day was an understatement, and an oversimplification of this complex phenomenon. Years later, after receiving a PhD, publishing a few scientific papers, while I am finding joy in the complexity of this universe, I get reminded of that question, and I ask the same question to myself that I asked that day; Why the hell is this fast munnkey running on the train?
My years of Aristotalian quest of a philosophical understanding has led me to understand following things, (or raise these further questions):
1) Munnkey is really fast.
2) He/She is quite an adrenaline-junkie. Running on a running train falls is the category of those Red Bull sponsored extreme events.
3) Where is he going? Does he have a family in other city/zoo. Is he running away from a zoo? Did he buy a ticket? If yes, then he can sit inside the train. There is no need to run on the top of train. Did he accidentally get stuck on the train? Was he just sitting, and train started moving. Maybe, he was double-crossed by some other bad monkey to meet him on the train top, right when the train moves.
4) If the intended destination of this train is not his/her real destination, and he/she accidentally got on this train, then how desperate his this monkey to get home? Will he/she jump on the other train going in the opposite direction to go back home. Can he/she do it successfully? Can he/she judge the speeds of all things moving, to do a good jump? Did my physics teacher try to help him/her out?
5) Owing to the serious implications of the previous point, I think the question of relative motion is bit flawed. The word relative itself is relative. I can calculate the relative speeds to a point on a train with no hesitation. Or a moving robot for that matter. But this is a sad, confused and adrenaline-high monkey. I have no idea how they perceive things under those conditions. I mean, you know how time seems to move slower when you are anxious or sad, or scared. Similarly, I don’t know if he is really seeing speeds as they are. So i don’t really know what is the relative speed of opposing train to the munnkey.
Summarily, it is a complex problem. Like the universe itself.