and the train is heading towards the person and the train hits the person and keeps going, does the train stop?
Confused??? So are we. my work mate says it has been scientifically proven that the train has to have stopped!, but we don't understand his explanation - can anybody please help before the rest of the office goes mad!!!
2006-11-17 03:03:11 · 21 answers · asked by geegee 4 in Science & Mathematics ➔ Physics
Thanks everybody - you have all agreed with the others in the office and the guy who set us this 'puzzle' can't find the correct answer at home !! Maybe next time he'll think before he asks silly questions as he knows I can get on to everybody out there and prove he's just being silly.
2006-11-19 21:54:52 · update #1
Simply put: no the train does not stop. Nor does the person whom the train hit, even when his direction changes. Assuming the train is significantly bigger than the person (in mass primarily)then the speed of the train will not be altered a noticable amount.
In practice this means the man is running at a certain speed immediately before the collision and immediately after he is moving in the opposite direction at the same speed as the train, assuming that he sticks (grusome)
It is the same principle that applys to a bouncy ball... it doesnt stop to change direction when it hits the ground.
This is a hard concept to get your head round at first, but trst me, this is what happens.
2006-11-17 07:18:56 · answer #1 · answered by Article 82 2 · 1⤊ 0⤋
No, its all to do with momentum. The person has a lot less momentum (mass times velocity (weight times speed)) compared to the the train. Fundamental physical rules state that the momentum must be conserved throughout an (elastic)collision. Therefore as the persons momentum changes from one direction to the other (Positive to neagtive) it instantaneously becomes zero, however at this instant the train is still moving because the the person had less momentum than the train to begin with.
To make the train stop all the momentum must be transfered to the person. Since the trains momentum is large compared to the persons mass the person would have to rebound off at a very high speed to compensate for the weight difference, which just doesnt happen.
Unless of course the persons mass is about the same as the train, then you have a kiddies train or a really obese person!!!!!!!
2006-11-17 03:17:33 · answer #2 · answered by Anonymous · 1⤊ 0⤋
No the train does not stop
You friend will say that at some point the velocity of the man = 0 (from the perspective of an observer) and since he is in contact with the train at that moment, the velocity of the train is also zero. This is not the case, the man will come to a halt for an instant, but the train continues on and deforms the mans body. So the man comes to a halt an instant before his relative velocity to the train becomes zero.
So the train never stops
As the man comes into contact with the train he decelrates (wrt to the train) until the relative velocity between him and the train become zero at this point the man is travelling in the same direction and at the same speed as the train.
2006-11-17 03:31:22 · answer #3 · answered by spoon_bender001 2 · 1⤊ 0⤋
Momentum is the product of mass and velocity, in simple terms the weight of an object times its speed. The momentum of the train is huge compared to the momentum of the person, hence scientifically it is impossible for the train to stop in this situation. The train might slow down, but the difference would be negligible. I bet some wise guy is pulling your leg, or this might be one of those lateral thinking puzzles. Id be interested in the explanation never the less.
2006-11-17 03:19:31 · answer #4 · answered by Mr Slug 4 · 1⤊ 0⤋
If a butterfly was heading toward an oncoming train, and the train hit the butterfly, would the train stop. Of course not. Same thing with a person.
The train will eventually stop at the next station, but not before.
2006-11-17 03:17:14 · answer #5 · answered by ironduke8159 7 · 1⤊ 0⤋
1.why would a person run towards a train?
2.why would it stop?
3.when it hits a small car does it stop?
4.do the people in the train know they are going to hit the person?
2006-11-17 03:14:18 · answer #6 · answered by 08 2 · 1⤊ 0⤋
only if the train is moving at exactly the same speed as the person and is not accelerating, then they will both stop, otherwise if the train is going faster it will lose a little kinetic energy, (equal to the speed the person was travelling at) but keep going, unless of course the driver realises what he has done and applies the brakes, which may have been what your mate was getting at, but thats just cheating
2006-11-17 04:11:09 · answer #7 · answered by Martin J 2 · 1⤊ 0⤋
Think about it this way: every moment a train (or any other object) is in motion, it is being hit constantly by objects, whether they be bugs, leaves, or just plain air. Air is every bit as much a substance as is a human being. If your friend's theory were true, all objects that appear to be in motion would actually always be stopped.
2006-11-17 03:50:14 · answer #8 · answered by bgdddymtty 3 · 1⤊ 0⤋
The unlucky person who got killed wouldn't have stopped the train but would have slowed it's momentum down, insignificantly.
A bit like a fly hitting your car, same effect or should I say no effect.
2006-11-17 03:14:40 · answer #9 · answered by Anonymous · 3⤊ 0⤋
You mentioned train but not how big is the train. If its a toy electric train and it hits you while you playing it would derail and stop.
2006-11-17 03:31:42 · answer #10 · answered by goring 6 · 1⤊ 0⤋