A relativistic puzzle, and more.

[arkain101]

This puzzle can be tricky, depending on your wit and background of physics however. Once we find the solution (which shouldnt be all that difficult) I plan to lead on to something further. That something further I will save for later.

 

Some will find this trivial.

 

 

First, the puzzle.

Consider two objects.

 

Object 1: A semi-circle on its side, acting as a ramp.

example: http://www.abcteach.com/basicshapes/images/semici4.gif

 

Object 2: A ball.

 

 

Procedure:

 

To have the ball roll along the ramp from two different points of view.

 

1)When someone is at rest with the ramp. And the ball is moving.

-The ball rolls, hits the ramp, and shoots back towards the direction it came from.

 

2)When someone is at rest with the ball. And the ramp is moving.

-The ball rolls up the ramp, but then continues moving along with the ramp. It does not shoot away from the ramp.

 

 

 

Question:

 

Why does the ball continue moving from one perspective, and come to a stop in the other perspective?

 

 

 

Purpose:

 

To elaborate on relativity. And Have Fun!

[Janus]

I'm sorry, but I can't make heads or tails of your "puzzle". You show an image of a semi-circle, but what do you mean by it "acts as a ramp". How does it act as a ramp? Where is the ball in this puzzle? I can find no way to reconcile the image with the accompanying text.

 

I also know of no situation where, depending on reference frame, the ball and ramp would act as you describe.

 

You are going to have to do a better job of explaining what you mean.

[arkain101]

I'm sorry, but I can't make heads or tails of your "puzzle". You show an image of a semi-circle, but what do you mean by it "acts as a ramp". How does it act as a ramp? Where is the ball in this puzzle? I can find no way to reconcile the image with the accompanying text.

 

I also know of no situation where, depending on reference frame, the ball and ramp would act as you describe.

 

You are going to have to do a better job of explaining what you mean.

 

Heh. Agreed. I'll have to get an art program installed again.

[Adamdellow86]

Inertia (the resistance of any physical object to a change in its state of motion).

[lawcat]

Inertia (the resistance of any physical object to a change in its state of motion).

 

Why is this a relativity or inertia problem at all. Rather, the problem strikes me as an incomplete balistics problem in which no infomration about mass or velocity is given. The immovable object and irresistible force paradox. In first, the ramp is the immovable object, in the second the ramp is the irresistible force. So the problem is a force problem, and for that we need some motion and mass information--hence balistics.

 

(or the puzzle lies in the 3d vs/ 2d perspective.)

[arkain101]

Its been awhile since I've thought about this but after reading it over again (kind of at random today) I think another way to explain it is like this:

 

If a skateboarder shoots down into a half-pipe ramp. He will travel down the ramp and up the other side and if we exclude gravity on the way back up the skater will shoot back in the direction he came from. (in this case the velocity of the skater remains constant throughout and the ramp is at complete rest)

 

However. If the skate boarder is sitting still and the ramp comes to him will the skateboarder travel along the ramp with same result? Or will the skate boarder be unable to leave the ramp and find himself at rest with it.(in this case the velocity of the ramp remains constant throughout and the skater is at complete rest)

 

I'd provide an answer but today is one of those days I'm just far to exhausted to bother.... I'm just about typing with my eyes closed lol.