# Relativity

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• 02-10-2005
Sang-drax
Relativity
Let's say we have a ball and a hole. The ball is slightly larger than the hole, so it won't fit.

Now we throw the ball at an enormous speed direclty towards the hole. What happens?

(i) (From a person standing beside the hole's POV)
The ball is slightly smaller than the hole and will pass through.

(ii) (From a person standing on the ball's POV)
The hole is much smaller than the ball, so it'll crash when it arrives.

What will happen?
• 02-10-2005
laserlight
The ball's mass increases drastically leading to an increase in size so it covers the whole hole and more?
• 02-10-2005
frrossk
What will be the point of view of a person standing between ball and hole? :D
• 02-10-2005
Govtcheez
> The ball's mass increases drastically leading to an increase in size so it covers the whole hole and more?

Just because it increases in mass doesn't mean it gets larger.
• 02-10-2005
laserlight
Quote:

Just because it increases in mass doesn't mean it gets larger.
That's why I assumed that it does.
On second thought, maybe there is negligible increase in mass, but instead the ball burns up and the little that's left of it passes through the hole.
hmmm....
• 02-10-2005
Clyde
Quote:

What will happen?
I have no idea, but be sure to post the answer when you find out.
• 02-10-2005
Sang-drax
Quote:

Originally Posted by frrossk
What will be the point of view of a person standing between ball and hole? :D

The position doesn't matter, only the relative speed to the ball.

Quote:

Originally Posted by frrossk
The ball's mass increases drastically leading to an increase in size so it covers the whole hole and more?

No.
• 02-10-2005
Thantos
Well you said that the ball is slightly larger then the hole. If its thrown with enough force and if its thrown accuractly then the force of the ball hitting the hole's edges would be enough to reshape the ball so that it would fit through the hole. Once it was through the hole the ball would return to its native shape.
• 02-10-2005
CornedBee
In any case, it has nothing to do with relativity. Oh, and the person between ball and hole will get the ball in the face.
• 02-10-2005
Lithorien
The ball will fit through the hole, because as it goes faster, it elongates and thins out.
• 02-10-2005
Brian
perspective != relativity
• 02-10-2005
laserlight
Quote:

perspective != relativity
Sang-drax might be thinking of frames of reference, but I'm not exactly very strong in the concepts involved in relativity to comment with any authority on it anyway.
• 02-10-2005
Sang-drax
OK, I think I've figured something out.
If the ball travels perpendicularly towards the hole, the ball will only look shorter in the direction of motion to the observer. The ball will look like somebody sat on it.
Same for the hole.

Thus, both observers will agree on the size of the ball in the other dimensions and it still won't fit.

Sounds reasonable.

Quote:

Originally Posted by Brian
perspective != relativity

No, but things will look different from different points of view. Events can even be happening in different order, depending on your relative speed to the objects you study.
• 02-10-2005
major_small
who cares? stop trying to put the square peg in the round hole... the solution is simple: make the hole bigger or the ball smaller.

either way, if the ball is malleable enough, and the force is constant, the ball will elongate into an ellipse and fit through the hole, but as you said, the ball is 'thrown' at the hole, so now it comes down to time. if the ball has enough time to regain it's shape by the time it hits the wall, it will hit the wall. if the ball gets to the hole before it regains it's shape, it'll get through.
• 02-10-2005
Zach L.
Uhh... Been a bit since I've done relativity, but shouldn't the ball only "deform" in the direction it is traveling. (And no, it won't turn into an ellipse and thin out.)

So, if it's going straight for the hole ("straight" meaning directly at some projection of it -- i.e. at an angle would work so long as the trajectory takes it through the hole), then it should make it through so long as it would under non-relativistic circumstances. If it isn't on a trajectory that goes through the hole, it has bigger problems to worry about.
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