does a fly stop a train when it hits the wind screen head on?

Question

some thing to do with that before a body can change direction it must stop. therefore when the fly hits the wind screen it stops before it changes direction and if it has stopped the the train must be stopped as it is in front of the train

Answer 1

The question should be does the train change its direction of motion? Obviously it does not. In fact it would be very difficult to measure the speed of the fly as being 0 m/s since the duration of its stop and change of direction would be infinitely small.
Consider your last sentence starting with "and if it has stopped". It doesnot make sense.
The momentum of the train is so much larger than the momentum of the fly, so that the fly's influence on the train would not even be measureable.

Answer 2

Remember that a fly is not a solid object. Start with the fly's nose. This will hit the windscreen and change direction. At the precise moment of impact, ie during the transition from going forward to going backwards attached to the windscreen, the nose will stop. The rest of the fly, however is still heading in the original direction. The point of contact, however travels up the fly's body until there is no more body and you have a splat on the windscreen.

Answer 3

A little common sense dispels this notion:
if the fly stopped the train, then the train decelerates and then accelerates rapidly enough to leave the speedometer unaffected in real terms. Such rapid speed changes would cause cause passengers, cans, cups, luggage etc. to be thrown about wildly, not to mention causing the train to derail; something that has never occurred even when a train hits a swarm of flies. Likewise, a meteorite hitting the earth or moon doesn't cause either of them to stop.

PS the last thing to go through the fly's head as it hits the windscreen? its backside.

Answer 4

Yes in theory it does.

At the exact point in time that the fly hits the train it will stop the area of the train that it hits for a fraction of a second. However, this fraction of a second is so small and the area of the train it hits is only the same size as the body of the fly we don't notice it.

However, it won't stop the whole train. Only the place of impact.

Answer 5

No. The fly can't stop the train because it doesn't have momentum equal to that of the train. Momentum is mass times velocity, and since the mass is far less than one percent of the train's, the fly's velocity would need to be SUPER supersonic to ever stop a train. Not possible.

There is an instant though (a time interval of zero) when the velocity of the fly is zero, as it reverses direction, because the train certainly had enough momentum to do that.

Answer 6

Agreed. You need to look up the Law of the Conservation of Linear Momentum.

M_train*V_train1 + M_bug*V_bug1 = (M_train+M_bug)*V_train2

where V_train1 and V_bug1 are the velocities of the train and bug before impact, and V_train2 is the velocity of the train after impact. (I am assuming the bug gets stuck to the train when they collide and does not bounce off - a perfectly inelastic collision).

So the only way the train and bug will both stop is if either

1) The train is moving insanely slow, at which point friction would have stopped it.
2) The bug is moving incredibly fast, unlikely.
3) The bug is huge, at which point it would be more like a train itself!

Answer 7

The instant that the flies backside travels through its brain is the instant that it isn't really moving... relative to the ground.

Of course if you consider the absolute motion, the fly was probably moving in the same direction as the train all along but not at the same speed, hence the collision.

Answer 8

this question is concerning artwork, power and power. Simlar question, think you're pushing a cycle, it rolls. Now you're pushing Bus (engine off and in impartial), the bus nonetheless rolls on the line, now you're pushing a wall, it wont pass. Supose you alongside with one hundred pals push a similar wall it is going to pass and finally crumple. in basic terms think of of the excuses. precisely in a similar style, the fly while hits the shifting prepare that's rushing at great velocity in the different direction, the prepare's velocity is decreased (could be very very very minutely) for an infinitely small time. yet because of gained momentum, the prepare pushes the fly and keeps its action.

Answer 9

I'm not sure about it stopping, but I know the last thing that went through the fly's mind before it died.......


It's backside!!!!!!

lol

Answer 10

I got into an argument once with a physicist about this. He insisted it does, for a mere fraction of a second.

I think it's bull*?@t.