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Forum index » Science and Technology » Physics » Relativity
puzzle in relativity
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Puppet_Sock
science forum Guru Wannabe


Joined: 17 May 2005
Posts: 124

PostPosted: Tue Jul 11, 2006 5:37 pm    Post subject: Re: puzzle in relativity Reply with quote

cafeinst@msn.com wrote:
[very old chestnut, often dealt with]

The real puzzle is why so few people can discover the difference
between sci.physics.relativity (where such is on topic) and
sci.physics (where it is not).
Socks
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Phineas T Puddleduck
science forum Guru


Joined: 01 Jun 2006
Posts: 759

PostPosted: Tue Jul 11, 2006 5:21 pm    Post subject: Re: puzzle in relativity Reply with quote

In article <1152637869.057294.313330@35g2000cwc.googlegroups.com>,
<cafeinst@msn.com> wrote:

Quote:
I found this here:
http://www.geocities.com/ResearchTriangle/System/8956/problems/probs.htm

"Five stuntmen are riding upon a large sled across an icy pond. In the
center of the pond is a hole exactly the same size as the sled, and the
stuntmen are travelling towards it at near the speed of light. When
they reach the hole, a man standing beside the hole hits the sled with
a sledgehammer to drive it into the hole. According to the stuntmen,
the hole decreases in length due to the effects of special relativity,
and thus they slide over and do not fall in. But the man standing
beside the hole sees the length of the sled decrease due to relativity,
and so the sled slips easily into the hole. Clearly the stuntmen or the
hammer man cannot both be right, so what happens?"


This is a form of the barn, or pole paradox

http://www.phys.unsw.edu.au/einsteinlight/jw/module4_pole_paradox.htm

http://www.oberlin.edu/physics/dstyer/Einstein/SRBook.pdf

--
Relf's Law? -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
"Bullshit repeated to the limit of infinity asymptotically approaches
the odour of roses."
Corollary -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
³It approaches the asymptote faster, the more Œpseduos¹ you throw in
your formulas.²
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
³Gravity is one of the four fundamental interactions. The classical
theory of gravity - Einstein's general relativity - is the subject
of this book.² : Hartle/ Gravity pg 1
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Jaffa cakes. Sweet delicious orange jaffa goodness, and an abject lesson
why parroting information from the web will not teach you cosmology.
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Sue...
science forum Guru


Joined: 08 May 2005
Posts: 2684

PostPosted: Tue Jul 11, 2006 5:20 pm    Post subject: Re: puzzle in relativity Reply with quote

cafei...@msn.com wrote:
Quote:
I found this here:
http://www.geocities.com/ResearchTriangle/System/8956/problems/probs.htm

"Five stuntmen are riding upon a large sled across an icy pond. In the
center of the pond is a hole exactly the same size as the sled, and the
stuntmen are travelling towards it at near the speed of light. When
they reach the hole, a man standing beside the hole hits the sled with
a sledgehammer to drive it into the hole. According to the stuntmen,
the hole decreases in length due to the effects of special relativity,
and thus they slide over and do not fall in. But the man standing
beside the hole sees the length of the sled decrease due to relativity,
and so the sled slips easily into the hole. Clearly the stuntmen or the
hammer man cannot both be right, so what happens?"

If the inertia of the hammer is equvalent to the specific gravity of
the water in the pond, I'd say their wrist watches will probably
shatter. Surprised)

"Retarded potential"
http://farside.ph.utexas.edu/teaching/em/lectures/node50.html

Sue...
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Craig Feinstein
science forum Guru Wannabe


Joined: 24 Mar 2005
Posts: 100

PostPosted: Tue Jul 11, 2006 5:11 pm    Post subject: puzzle in relativity Reply with quote

I found this here:
http://www.geocities.com/ResearchTriangle/System/8956/problems/probs.htm

"Five stuntmen are riding upon a large sled across an icy pond. In the
center of the pond is a hole exactly the same size as the sled, and the
stuntmen are travelling towards it at near the speed of light. When
they reach the hole, a man standing beside the hole hits the sled with
a sledgehammer to drive it into the hole. According to the stuntmen,
the hole decreases in length due to the effects of special relativity,
and thus they slide over and do not fall in. But the man standing
beside the hole sees the length of the sled decrease due to relativity,
and so the sled slips easily into the hole. Clearly the stuntmen or the
hammer man cannot both be right, so what happens?"
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Google

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