Private Rocket Launch Tests Supersonic Parachute and Reusable Tech


A private spaceflight company, Armadillo Aerospace, is reviewing their test data from a rocket test in the New Mexico desert. The flight encountered problems while testing a new launch and balloon parachute technologies, but the company remains one of the leading private entities in the industry.

Read more @ SciTechDaily

NASA’s Toxic Test Chamber Allows Hellish Venus-Like Conditions on Earth


In an effort to learn how their technology will react to the hellish surface conditions on Venus, NASA engineers will put together a 12-ton toxic oven in Cleveland at the NASA Glenn Research Center. It will be operational in May 2012, and scorch anything that is put in it at 1,000 degrees Fahrenheit, as well as crush it at nearly 100 atmospheres, then choke it with carbon dioxide, sulfuric acid and other noxious fumes.

Read more @ SciTechDaily

LEGO Robot Helps Test iPad Apps, Promises Not to Make Any In-App Purchases

Developers, what do you do when you don’t feel like testing your apps yourself? You built a LEGO Mindstorms robot to do the job for you. That’s basically what researchers and developers at the Pheromone Lab did recently. Their LEGO robot helped them test an app by taking 10,000 photos with it.

pheromone lab app tester lego mindstorms robot ipad

Read more @ Technabob

2004 Yamaha Cygnus X 125cc

2004 Yamaha Cygnux X

I handed over Green Kelly last Thursday for the final tune-ups. She had started to grow on me over the last week, and except for a few tweaks here and there, she was fine.

The scooter shop owner handed over a 2004 Yamaha Cygnus 125cc as a loaner. I’m currently thinking about trading in Green Kelly for this scooter. When I first rode it, I was somewhat surprised. It’s got good early acceleration, but then it tapers off midway and only comes back in force once you hit max speed. This scooter weighs somewhat more than the Yamaha Forte, but it feels a lot stabler at mid to high speeds. It feels quite solid at higher speeds, and the bumps in the road seem less of an issue.

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Rational And Irrational Numbers

Rational Numbers

In mathematics, a rational number is a number which can be expressed as a ratio of two integers. Non-integer rational numbers (commonly called fractions) are usually written as the vulgar fraction a / b, where b is not zero. a is called the numerator, and b the denominator.

Each rational number can be written in infinitely many forms, such as 3 / 6 = 2 / 4 = 1 / 2, but it is said to be in simplest form when a and b have no common divisors except 1 (i.e., they are coprime). Every non-zero rational number has exactly one simplest form of this type with a positive denominator. A fraction in this simplest form is said to be an irreducible fraction, or a fraction in reduced form.

The decimal expansion of a rational number is eventually periodic (in the case of a finite expansion the zeroes which implicitly follow it form the periodic part). The same is true for any other integral base above one, and is also true when rational numbers are considered to be p-adic numbers rather than real numbers. Conversely, if the expansion of a number for one base is periodic, it is periodic for all bases and the number is rational. A real number that is not a rational number is called an irrational number.

The set of all rational numbers, which constitutes a field, is denoted \mathbb{Q}. Using the set-builder notation, \mathbb{Q} is defined as

\mathbb{Q} = \left\{\frac{m}{n} : m \in \mathbb{Z}, n \in \mathbb{Z}, n \ne 0 \right\},

where \mathbb{Z} denotes the set of integers.

Irrational Numbers

In mathematics, an irrational number is any real number that is not a rational number — that is, it is a number which cannot be expressed as a fraction m/n, where m and n are integers, with n non-zero. Informally, this means numbers that cannot be represented as simple fractions. It can be deduced that they also cannot be represented as terminating or repeating decimals, but the idea is more profound than that. While it may seem strange at first hearing, almost all real numbers are irrational, in a sense which is defined more precisely below. Perhaps[1][2] the most well known irrational numbers are π and \scriptstyle\sqrt{2}.

 \Bbb{R} \ \mathbb{Q} denotes the irrational numbers.

Having read the above recap on rational and irrational numbers, try answering the following multiple choice question which I had in a test today:

Which of the following is the first false statement?

(a) Between two different rational numbers, we can always find another rational number.
(b) Between two different rational numbers, we can always find an irrational number.
(c) Between two different irrational numbers, we can always find a rational number.
(d) Between two different irrational numbers, we can always find another irrational number.
(e) 0 = 1.

Continue reading “Rational And Irrational Numbers”