A fly, flying around inside a car

[kermit911]

Hi all, my wife asked me why doesn't a fly that is flying around in a car get plastered against the back of the windshield when she accelerates from 0 to 60 in 4 seconds? I told her it is because there is no outside force hitting the fly. If you were in a convertible the fly would be thrown out the back. Is that anywhere close to being correct?

Thanks
Dave

[jake-the-peg]

Pretty much

The air inside the car is accelerated along with the car and that pushes on the fly.

In a convertible the air would rush out taking the fly with it

[wildwood]

No dinner for Mrs Kermit tonight then...

[joggerjayne]

What if the inside of the car was a vacuum ... ?

Would the entire vacuum move, with the fly inside it ?

Or would the absence of any air to move the fly cause it to splat on the rear window ?

[4getmenot]

my blokes answer is much better 'shut up you stupid woman'

[jake-the-peg]

If there were a vacuum in the car the fly would not ..er.. fly so we have to change thae analogy a bit.

Lets assume that we drop a marble in the space shuttle's hold and it hangs in space. When the shuttle accelerates there will be no forces acting on the marble and it will hit the back of the cargo bay wall.

Or rather the cargo bay wall will hit it!

[jomifl]

How do you know it doesn't, how many flies have you watched in a car?

[mibn2cweus]

Six inches of foam rubber glued to the back window . . . worries are over!