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Physics Puzzler - 7/6/2006 3:15:29 PM   
Dsegal


 

Posts: 1817
Joined: 10/20/2002
From: Philadelphia, PA, USA
Status: offline 		Many decades ago I read a series of science puzzles in Scientific American magazine and one of them has stuck with me as I don't know the answer. Take a metal disk with a hole in the center, like a washer. Heat the disk and the outside diameter increases. What happens to the inside diameter? Does anyone have a certain answer?

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Dave Segal
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RE: Physics Puzzler - 7/6/2006 4:00:27 PM   
ClemenTang


 

Posts: 665
Joined: 8/18/2004
From: , HONG KONG
Status: offline 		Ever replaced an engine bearing? You heat the crankcase and the bearing falls out.

Clement

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RE: Physics Puzzler - 7/7/2006 5:53:55 PM   
Dsegal


 

Posts: 1817
Joined: 10/20/2002
From: Philadelphia, PA, USA
Status: offline 		And to think of all of those nights I lay in bed staring at the ceiling and worrying about this! (G) Thanks for your reply.

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Dave Segal

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RE: Physics Puzzler - 7/21/2006 1:14:19 PM   
MinnFlyer



Posts: 20182
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline 		Ok, then let this one keep you awake for a while:

You go on a trip with two other guys.

You get a hotel room. The kid behind the desk says the room is $30 a night. So you each pay $10.

Later, the manager reminds the kid that this week they have a $25 special, so he over charged them and to give them back $5

On the way to the room, the kid figures, "$5 doesn't split equally between 3 guys" so he pockets $2 and gives them back a dollar each.

Now here's the problem... Now the guys only paid $9 each - That's $27. Plus the two that the kid put in his pocket equals $29

Where did the other dollar go???

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Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

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RE: Physics Puzzler - 7/21/2006 2:11:10 PM   
MajorTomski



Posts: 1417
Joined: 5/1/2003
From: Oklahoma City, OK, USA
Status: offline
quote:

ORIGINAL: MinnFlyer

Ok, then let this one keep you awake for a while:

You go on a trip with two other guys.

You get a hotel room. The kid behind the desk says the room is $30 a night. So you each pay $10.

Later, the manager reminds the kid that this week they have a $25 special, so he over charged them and to give them back $5

On the way to the room, the kid figures, "$5 doesn't split equally between 3 guys" so he pockets $2 and gives them back a dollar each.

Now here's the problem... Now the guys only paid $9 each - That's $27. Plus the two that the kid put in his pocket equals $29

Where did the other dollar go???


There's $25 in the hotel till.
the guyes gave the hotel 3x $9 or $27 the clerk kept $2 so $27 to the hotel, less the $2 the kid kept is the $25 in the till.

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RE: Physics Puzzler - 7/26/2006 4:25:52 AM   
BTerry



Posts: 960
Joined: 4/24/2002
From: Silverdale, WA, USA
Status: offline 		$25 doesn't divide evenly between 3 people, it comes to about $8.33. Give a buck back to each of the customers, and they have effectively paid $9.33 which rounds just about equals $28 ($27.99).

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RE: Physics Puzzler - 7/29/2006 4:24:49 AM   
Hossfly



Posts: 3988
Joined: 12/3/2001
From: New Caney, TX, USA
Status: offline 		MinnFlyer's problem was first told to me by my Dad when I was a grade school kid. (I'm 70 now)

There are a number of explanations however as presented, the $1 is definitely a mystery.

If I lay down $10 and I receive $1 back, I have paid $9. True even in the new math!

At a party, it makes for a good conversation item after a few beers.

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H. Cain AMA L-93, CD - 1963, Leader - 1964

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RE: Physics Puzzler - 7/31/2006 11:58:58 PM   
sfsjkid



Posts: 579
Joined: 12/12/2003
From: fremont, CA, USA
Status: offline 		The way I see it, the kid did pocket the $2 before hand, then with remaining, three dollars in hand, gave each kid a buck back, including himself.

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RE: Physics Puzzler - 8/1/2006 3:22:42 PM   
MajorTomski



Posts: 1417
Joined: 5/1/2003
From: Oklahoma City, OK, USA
Status: offline
quote:

ORIGINAL: Hossfly


If I lay down $10 and I receive $1 back, I have paid $9. True even in the new math!




RIGHT the HOTEL got only $27 (3x9) the kid kept $2, there's $25 left in the hotel till. The trick in the question tries to get you to add $2 to the $27, not subtract it as is the case

$30 out of their pockets into th hotel drawer
-$3 back to them leaves
$27, minus the $2 to the clerk
leaves $25 in the hotel drawer.




(in reply to Hossfly)
       Post #: 9

RE: Physics Puzzler - 8/1/2006 4:35:36 PM   
MinnFlyer



Posts: 20182
Joined: 4/22/2002
From: Willmar, MN, USA
Status: offline 		Major Tomski's answer is correct.

It is a trick question - the figure $30 is no longer valid. $25 dollars is the correct figure. So 3x9=27 MINUS the $2 = $25

_____________________________

Mike B.
AMA# 42400 www.gettingairborne.com

"Those are my principles. If you don't like them, I have others." - Groucho Marx

(in reply to MajorTomski)
       Post #: 10

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