A wasp was flying along at 10 mph when........

[Spriddler]

........it became squashed on the windscreen of a train coming head-on out of a tunnel at 60mph.
At the moment before the direction of the wasp reversed through 180 degrees when it became squashed on the train's windscreen it must have been stationary for a fraction of a moment, but the train didn't stop................................

 

[Podney]

Yes,that makes sense.

 

[dunnah01]

The train did slow down a bit on impact though..

 

[meanders]

Good grief where did you dig that up from? Had that set only with a fly rather than a wasp at college 50 odd years ago.

The answer is in the relative mass. If the wasp weighed even 1% of the train mass, a tiny deceleration would be detectable. I guess with modern day instrumentation or laser scanning of the screen, a tiny deflection or flex might be measurable on the screen, but why would you bother.

 

[suavecarve]

I suspect the last thing to go through that wasps mind was its arse

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[funflair]

So if a cage full of pigeons being transported by plane escape and start to fly around does the plane weigh any more or less?

 

[chaser]

It used to be said that steam rollers were kept in service long after diesel rollers came in because they could go from forwards to reverse in an instant and vice versa, so not leaving ridges in the tarmac when rolling whereas diesel had to stop and change gear while sinking in.

 

[pappajohn]

They both stopped on impact for a fraction of a nano-second.
Stands to reason, if the fly stopped so did the train

 

[movan]

Poor ickle wasp.

 

[David and Sally]

So if a cage full of pigeons being transported by plane escape and start to fly around does the plane weigh any more or less?

No. Because the weight of the birds is being taken by the air in the plane, which in turn is borne by the plane.

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[David and Sally]

They both stopped on impact for a fraction of a nano-second.
Stands to reason, if the fly stopped so did the train

Surely not. The inertia of the train far outweighs that of the wasp. The train would lose some speed but not much. If the train stopped momentarily then it would have to accelerate back to speed instantaneously, which it can’t.

 

[pappajohn]

So if a cage full of pigeons being transported by plane escape and start to fly around does the plane weigh any more or less?

It weighs less by the total weight of the pigeons.

 

[pappajohn]

If you have a helium filled balloon in your car and you brake hard does the balloon move forwards.

 

[Tombola]

If tree falls in the woods and no one was around ........???

 

[movan]

I've gone brain dead. . I love stuff like this. You lot are so clever.. but I lie awake at night trying to work it out!!!

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[tonyidle]

Backwards. It's lighter than air which moves forwards.

 

[pappajohn]

If tree falls in the woods and no one was around ........???

Still makes a noise.... Sound waves will still be made.

 

[Spriddler]

No. Because the weight of the birds is being taken by the air in the plane, which in turn is borne by the plane.

Much the same as if you're over payload weight when stopped in the m/h at a checkpoint. It would make no difference if you were to drink all of the booze on board........ but fun nevertheless.

 

[pappajohn]

Backwards. It's lighter than air which moves forwards

Doesn't move. There are no forces acting on it.

 

[Tombola]

Still makes a noise.... Sound waves will still be made.

but it isnt sound until the wave reaches an eardrum and is turned into audio ?

OR IS IT !!!!!!

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[David and Sally]

Doesn't move. There are no forces acting on it.

But it has velocity. It is moving relative to the earth and will continue to move just as a passenger does although no forces are applied to the passenger.

 

[movan]

The only intelligent contribution I can make here with a big word is that it's the transitional period of the wasp that is the query.

I like ballroom dancing.

 

[pappajohn]

but it isnt sound until the wave reaches an eardrum and is turned into audio ?

OR IS IT !!!!!!

If sound waves are present so is noise.... Can't have one without the other.

 

[tonyidle]

Doesn't move. There are no forces acting on it.

There are. The air within the vehicle has mass and therefor momentum. It will move forwards to displace the less dense balloon. The visible effect will be the balloon moving towards the rear. More information here:

Broken Link Removed

 

[pappajohn]

But it has velocity.

So does the free air in the car, the air will reduce velocity at the same rate as the car... And the balloon is floating in that air.

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[tonyidle]

If sound waves are present so is noise.... Can't have one without the other.

Noise only exists if pressure waves are able to cause something to vibrate.

 

[funflair]

If you have a helium filled balloon in your car and you brake hard does the balloon move forwards.

Good question but you are wrong re the pigeons so try again

 

[Tombola]

If sound waves are present so is noise.... Can't have one without the other.

If thunder is created and a person who is completely deaf cant hear it because his / her ear hasnt turned the waves into sound then there is no sound

 

[pappajohn]

Noise only exists if pressure waves are able to cause something to vibrate.

Nobody can hear you scream in space.

 

[David and Sally]

So does the free air in the car, the air will reduce velocity at the same rate as the car... And the balloon is floating in that air.

I think the air will continue to travel, as will the balloon because they have mass and hence kinetic energy. The air will increase in pressure in the front of the car and reduce in the rear until it is all equalised . The balloon will continue to travel until air resistance absorbs what small kinetic energy it has.

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