Solving the Rubik's Cube Blindfolded

There are many methods to solve the Rubik's Cube blindfolded. In this post, I will be explaining the concept of solving a 3x3x3 Rubik's Cube, in a very brief manner.

Brief explanation of the concept:
Since we are solving the cube blindfolded, we will have to assign a buffer location (something like a temporary storage). Send the piece located at the buffer to its right place, doing so will result in exchanging another piece back into the buffer. This process repeats itself until the whole cube is solved.

Basically, the cube can be categorized into edges and corners. You can choose to solve either one first.

For example:

A scrambled cube:

Cube with corners solved:

Cube with edges and corners solved:

Here are some of the methods used by fellow 'cubers' to solve the cube blindfolded:
Edges:
M2
Old Pochmann
TuRBo edges
3-cycle edges

Corners:
3OP
R2
Old Pochmann
TuRBo corners
BH

Here's a video of me solving the cube blindfolded. My personal best to date (28 November 2011).
I rather not.

Artificial Gravity

Some might have wondered how artificial gravity works. Now, we'll have a brief explanation about it. But before we discuss more about it, let's define what's artificial gravity.

According to Mr Wiki, artificial gravity is the manipulation of gravity by artificial means, either increasing or decreasing. For example, making artificial gravity in spaceships is increasing the gravity felt by the astronauts while the free-falling of a plane creating weightlessness is a good example of decreasing gravity.

We'll just talk about increasing or making artificial gravity.

The idea is to rotate a ship as fast as possible creating high angular velocity. There will be a proportional force generated called the centripetal force (F), given by:

 

where the character that looks like 'w' (called omega) is the angular velocity. The centripetal force is the force acting on the joint attaching the outer ship (or ring) to the centre (or origin). The direction of this centripetal force is towards the origin of rotation. Subsequently, there exists an equal and opposite force called the centrifugal force, which acts on the body or outer ring. Since the direction of the force is opposite, the centrifugal force pulls the body outwards.

I will give an example to ease the understanding. Imagine you are playing with hammer throw.

The centripetal force acts on the metal chain attached to the heavy hammer at the end of the chain, towards you. On the other hand, the centrifugal force acts on the hammer at the end of the chain, away from you.

Returning to our space station example: 

The astronauts will be located at the outer ring of the space station. When the space station rotates, the resultant centrifugal force will pull the astronauts away from the centre of the ring, causing an artificial gravity outwards.

Hence, to create more artificial gravity, you need to spin faster and at the same time, have a large radius. This will create a large centripetal force, which results in large centrifugal force.

Balancing a coin on a piece of paper

The ultimate goal is to achieve this:

which is balancing a coin on a piece of folded paper.

HOW:

Prepare a coin and a piece of paper or bill.

Fold the piece of paper in half, with its longer sides touching each other. Then...

You wouldn't want to try to balance it this way:

or this way:

There's a trick to it. Fold the folded piece of paper in half like this: 

Place the coin on it: 

Then start pulling each side of the paper away from the middle:

 

There you go! Good luck and have fun. You can use money bill if you wish so that it is convenient to do this trick anywhere at any time.

Filtering Vuvuzela Sound

In case you don't know what's a Vuvuzela, here's a pic taken from wikipedia.

This instrument is made famous when South Africa hosted the FIFA World Cup in 2010. Stadium audience blow the Vuvuzela horn to make sounds, not sure to cheer or to distract the players. There were a lot of complaints during the World Cup, about the sound being an irritation to the players, supporters, TV audiences.

Supplement information: The Adidas Jabulani ball is used as the official World Cup ball for that year. It received many criticism for its 'unpredictable behaviour'. Cristiano Ronaldo would love to use it to his advantage against goalkeepers.

Back on track, so the challenge is to remove the Vuvuzela noise from an audio clip that consists of human commentary, Vuvuzela noise, stadium sound and noise from other sources.

I will be talking about the concept and methodology that I know of to remove the Vuvuzuela sound.

The Vuvuzela gives a B-flat note and its harmonics. According to http://www.wired.com, it has a fundamental frequency of 466.164 Hz. So you'll to filter out the fundamental frequency and its harmonics such as 932Hz, 1398Hz, 1864Hz, 2330Hz, 2796Hz, 3262Hz.... It is also recommended to filter 233Hz.

The human ear can hear from 20Hz to 20,000Hz, but the human speech only covers 400Hz to 5000Hz - http://www.csun.edu. Hence, you can filter out frequencies below 400Hz and above 5000Hz. In my opinion, you can safely remove any frequencies above 3500Hz.

To summarize, just apply bandpass filter to allow 400Hz to 3500Hz to pass through and apply bandstop filters at 233Hz, 466Hz, 932Hz, 1398Hz, 1864Hz, 2330Hz, 2796Hz and 3262Hz. It takes trial and error and you might have to tweak here and there to get the best out of it. Good luck and have fun!

Rubik's Cube

There are many types of Rubik's Cube puzzles - 2x2x2, 3x3x3, 4x4x4, 5x5x5 and so on. The picture above shows three 3x3x3 Rubik's Cube puzzle though they are not of Rubik's brand. Not to mention that there are other weird puzzles like Pyraminx, Square-1 and the list goes on. I will not go into each puzzle because I only know how to solve the 3x3x3 Rubik's Cube. However, I can share the concept to solve a 3x3x3 Rubik's Cube.


I will just refer to the 3x3x3 Rubik's Cube puzzle as cube from now on for convenience. There are many ways to solve the cube, to name a few relatively popular ones - Roux, Fridrich, Petrus. Well, the most famous of all and the method used by the current(Nov 2011) world record (WR) holder, Feliks Zemdegs is the Fridrich method (invented by Jessica Fridrich), also more commonly known as the CFOP method.


I will just explain the CFOP method in this post because it is the most famous method currently.
CFOP stands for - cross, first-2-layers(F2L), orientation-of-last-layer (OLL)and permutation-of-last-layer (PLL).


Scrambled cube below:



















Cross solved:



















F2L:



















Before executing OLL:



















After OLL:



















PLL:



















So that's the concept behind solving the 3x3x3 Rubik's Cube using the Fridrich method aka CFOP method.
For more detailed tutorial to use CFOP, please go to one of the following recommended sites:
badmephisto
cubefreak


FYI, there are multiple official competitions going on around the world as we speak. To find out more, you can go http://www.worldcubeassociation.org/. You can also join the community's forum at http://www.speedsolving.com.




MrExtra