Can a fly stop a train? If a fly is travelling towards a moving train and hits hits the windscreen...?

Question

there must be a moment when the fly is not moving towards the train or travelling with the train, therefore there must be a moment when the fly isn't moving at all. Therefore is there a moment when the train isn't moving? So can a fly stop a moving train.

Answer 1

There's a short period of time when the front end off the fly has changed direction and is travelling with the train, and the back end of the fly is still moving towards the train. That's during the s of splat. The train windsceen is slightly elastic and takes up the reciprocal movement.

Answer 2

Only if it’s flying at some incredible speed like a quarter of the speed of light would it even have a chance to stop the train. If it did it would only derail the locomotive and its cars. It simply doesn’t have the mass to bring to a stop it. Even more likely if was moving that fast it would shoot threw the locomotive like a bullet threw a big piece of wood. You would have change the density of the fly body in order to give it true fighting chance and still would only through the train from the tracks. I would only come to a stop when it settled on the ground. So I guess you could say the earth truly would stop the train and not the fly. So the answer is no.

Answer 3

Practically, No. The moving fly, in order to stop the train, must have the same force as the moving train. That would mean a very heavy fly or a very fast moving fly (Force = Mass X Acceleration). Also, if there is such a fly, the windshield will break first due to the force of the impact.

Answer 4

As Rob mentioned in his answer, you would need to fly's momentum to be greater than the trains. Even if you had a light train and a really heavy fly (some genetically modifies super fly), the fly would still have to move a reasonable fraction of the speed of light. At those speeds, the impact would instantly vapourize the fly, indeed the atoms of fly and train windscreen would undergo some very brief nuclear fusion reactions! The velocity of the impact would create conditions (mega heat and pressure) that would allow fusion.

Answer 5

The important point is that momentum must be conserved, this is a fundamental universal concept.
At the instant the fly stops moving in your example it will have lost all its momentum (it's mass x it's velocity). So the train must lose an equal amount of momentum.
As the train is massive compared to the fly, and probably faster, it has many times the momentum of the fly and so it's reduction in momentum will be negligible; this will appear as a tiny reduction in velocity - the train will slow by a negligible amount.
(to be strictly accurate we should take into account that the train's mass increases by that of the fly).
Incidentally, what would be the last thing to go through the flies brain as it his the train? Answer: it's butt!

Answer 6

I think that the oncoming force of the train would stop the fly in it's tracks .....so the train probably splatted the fly..The fly shouldnt have been hanging out in the wrong place at the wrong time. No fly is gonna travel the speed of a train! Question is..will a train stop a fly? yes

Answer 7

Interesting question but it's important to remember that everything is being pushed down at 9.8m/s^2. The flys forward movement stops when it is cancelled out an equal or greater force from the train. A fly also would never be able to generate enough force to break a train's friction coeffictient

Answer 8

Hello,
No. It can't. The moment the fly hits the train, it does exert a small force on the train, but not enough to cause the train to decelerate. The fly, on the otherhand, decelerates at a HUGE rate. The fly comes to a stop, because it goes from moving in one direction to moving in the opposite direction...the train doesn't .

Answer 9

If the FLY stops moving then the TRAIN must be affected by that. The forward movement of the TRAIN must be reduced by the same force required to STOP the fly.

NOT MUCH but it's something.

Good Question.

Answer 10

No..its all about momentum. There will be an instant when the fly has no velocity at all...and the fly will slow the train down by an infinitely small amount...but unless you find a fly big enough to derail the train...its not going to happen