Jump to content


Welcome to BrainDen.com - Brain Teasers Forum

Welcome to BrainDen.com - Brain Teasers Forum. Like most online communities you must register to post in our community, but don't worry this is a simple free process. To be a part of BrainDen Forums you may create a new account or sign in if you already have an account.
As a member you could start new topics, reply to others, subscribe to topics/forums to get automatic updates, get your own profile and make new friends.

Of course, you can also enjoy our collection of amazing optical illusions and cool math games.

If you like our site, you may support us by simply clicking Google "+1" or Facebook "Like" buttons at the top.
If you have a website, we would appreciate a little link to BrainDen.

Thanks and enjoy the Den :-)
Guest Message by DevFuse
 

Photo
- - - - -

Wired Equator


  • This topic is locked This topic is locked
67 replies to this topic

#61 Livewire

Livewire

    Newbie

  • Members
  • Pip
  • 1 posts

Posted 19 May 2008 - 12:15 PM

Wouldn't a flea jump over, rather than creep under the wire?

;)
  • 0

#62 KOOPA

KOOPA

    Newbie

  • Members
  • Pip
  • 1 posts

Posted 08 September 2008 - 06:59 PM

That makes no sense. Everyone is making it harder than it really is. Imagine the wire laying on the floor right in front of you running perfectly across the ground. Now pick a spot on that wire and cut it. Add 10M of more wire. Problem solved, now you can easily walk under it.
  • 0

#63 Moeficky

Moeficky

    Newbie

  • Members
  • Pip
  • 2 posts

Posted 02 November 2008 - 12:21 PM

sphere.JPG

The 10 meters isn't spread equally around the globe necessarily. If it were then the distance between the globe and the wire would be very small indeed. I'm sure one of these super brains could easily figure the distance if that were a condition.
  • 0

#64 zaim9999

zaim9999

    Newbie

  • Members
  • Pip
  • 2 posts

Posted 01 May 2010 - 04:02 AM

Well, the way I make it is
C= 40000000M therefore (Cx3.142857143/2=r) the Radius is 62857142.86 M
C= 40000000 + 10 is C = 40000010M therefore the radius is 62857158.57 M
62857142.86 - 62857158.57 is 15.71428571M.

Your answer of 1.6 M would be correct if the wire were only 1 M longer.

Or have I missed it completely?

the formula u used to calculating radius was r=C*(pi)/2
check the maths book dude its C/2*(pi)
  • 0

#65 YoDeucezKid

YoDeucezKid

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 25 June 2010 - 03:07 AM

Wouldn't a flea jump over, rather than creep under the wire?

;)

lol that's what my cousin said
  • 0

#66 NintendoMad

NintendoMad

    Junior Member

  • Members
  • PipPip
  • 66 posts

Posted 08 July 2010 - 11:17 PM

I have seen a very similar question to this....I really like this and found it very interesting.
This was the question I saw.
Lord Fimbleton lost 6 meters of his cricket fence, how much shorter would you expect the boundary, which was 50m away from the centre?
Only 1 meter shorter. So the radius is now 49 meters

Now the Gods also hold a cricket match, a very vast cricket ground, billions of miles across, but they have also lost 6 meters of fencing, how much shorter would their ground be?
1 meter. So the radius will be 1 meter shorter.

You would think that, for the second one, it would be less, but it isn't

This is why:

We know that the perimeter for a circle is P= 2pi*r

Lets do this simultaneously
Old P=2pi*Old r 1
New P=2pi*New r 2

2-1

New P-Old P=2pi*(New r-Old r)
6=2pi*(New r-Old r)
6/(2pi) = New r-Old r
which is approx. 1 meter. So the numbers don't matter. Doesn't matter how big or small it was to begin with. Don't let that deceive you.

I recommend to anyone who enjoys these, or similar, puzzles to buy and read 'Why do buses come in threes?' by Rob Eastway and Jeremy Wyndham. And their other books too. They are very good, interesting and enjoyable to read.
  • 0

#67 NintendoMad

NintendoMad

    Junior Member

  • Members
  • PipPip
  • 66 posts

Posted 08 July 2010 - 11:24 PM

Interestingly enough, it doesn't matter what the original diameter of the object is. If you add 10 meteres to the original circumference x, the change in radius will be 1.6 meters.

Here's the algebra: Solving for change in radius (R2-R1)

Knowns:
x1 = 2*Pi*R1
x2 = 2*Pi*R2
x1 = x2 - 10

Solution:
R1 = x1 / (2*Pi)
R2 = x2 / (2*Pi)

so by substitution, R2 - R1 = x2 / (2*pi) - x1 / (2*pi)
-or-
R2 - R1 = (x2 - x1) / (2*Pi)
then
R2 - R1 = [x2 - (x2 - 10)] / (2*Pi)

The x2's cancel out. The result, regardless of x2 or x1 is simply:

R2 - R1 = 10 / (2*pi) or 1.6

Crazy to think that whether the object is as small as marble, or as big as the galaxy if you add 10 to the circumference measuring tape, you can pass a small child underneath anywhere.


I know. It's quite mind blowing to think that. I posted a similar thing (I didn't look through all the posts). I saw this in a book (Why do buses come in threes) and it just goes to show just how wrong gut feelings can be, and how logic and maths can show it.
  • 0

#68 NintendoMad

NintendoMad

    Junior Member

  • Members
  • PipPip
  • 66 posts

Posted 08 July 2010 - 11:36 PM

VERY VERY Well Said! That's what I said minus all the educated words..lol


LOL! But yep...exactly. I also stated (and someone else did too) a similar illusion. Where you can remove or add the same amount to both a small and large object and still have the same difference.
e.g. a tennis ball(A) and tennis ball(B) being 7 cm bigger in circumference and a planet(A) and planet(B) being 7 cm bigger in circumference. They will both have the same difference in radius, but you wouldn't expect that as you would expect the planet to have a smaller change, because it's a bigger object.
What people need to remember is that the radius will increase/decrease by the same amount, regardless of the size of the object, BUT the change will be less significant in the larger object, as it was already huge.
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users