A NASA legyőzi a hangrobbanást

A hangrobbanás jelenségével azóta nem tudnak mit kezdeni a repülőtervező mérnökök, mióta Chuck Yeager, az amerikai légierő tesztpilótája először lépte át a hangsebességet egy kísérleti repülőgéppel 1947-ben.

Amit addig csak kicsiben, a karikás ostor csattanásakor érzékelt az ember, az egyre gyorsabb repülőgépek elterjedésével súlyos probléma lett. A NASA kutatói most úgy tűnik, jó úton haladnak, hogy elnémítsák a hangrobbanást.

Ha egy tárgy a levegőben halad, hanghullámokat kelt, amelyek hangsebességgel (tengerszinten 1225 km/h) terjednek, nagyjából úgy, mint a vízen haladó hajó által felvert hullámok. Minél gyorsabb az objektum, az általa keltett hanghullámok annál inkább összetorlódnak, majd a hangsebesség átlépésekor összeolvadnak egyetlen, nagy energiájú lökéshullámmá – ez a hangrobbanás.

A hangrobbanás miatt a szuperszonikus repülőgépek használhatósága eléggé korlátozott (nem véletlen, hogy a leghíresebb, hangsebesség feletti utasszállító, a Concorde is csak az Atlanti-óceán feletti útvonalakon járt), hiszen lakott területek felett nem tanácsos állandóan ilyen robbanásokat előidézni.

A NASA évek óta dolgozik a kereskedelmi célú szuperszonikus repülést visszafogó effekt legyőzésén, és úgy tűnik, most, papíron legalábbis, sikerül a 2006 óta zajló Quiet Spike projekttel. A repülő orrára szerelt, speciális anyagból épített, 7,3 méteres tüske szerepe, hogy a hanghullámokat úgy osztja szét, hogy három különálló, egymással párhuzamos kisebb lökéshullám keletkezik az egy nagy helyett, ezzel jelentősen csökken a robbanás hangereje.

Az amerikai űrkutatási hivatal Dryden Flight Research Center kutatóközpontjának munkatársai január végén mutatják be [1] a lehalkított hangrobbanás technológiáját.

Top 25 Oddball Interview Questions Of 2010

While we all know the interview process can seem like a bit of a stressful process, for some it can be downright grueling! We’ve culled through tens of thousands interview questions that job seekers from around the world have shared on Glassdoor over the past year and found some pretty off the wall stuff. Here’s our take on the top 25 oddball interview questions of 2010:

1. “If you were shrunk to the size of a pencil and put in a blender, how would you get out?” – view answers
Asked at Goldman Sachs. More Goldman Sachs interview questions.

2. “How many ridges [are there] around a quarter?” – view answers
Asked at Deloitte. More Deloitte interview questions.

3. “What is the philosophy of Martial Arts?” – view answers
Asked at Aflac. More Aflac interview questions.

4. “Explain [to] me what has happened in this country during the last 10 years.” – view answers
Asked at Boston Consulting. More Boston Consulting interview questions.

5. “Rate yourself on a scale of 1 to 10 how weird you are.” – view answers
Asked at Capital One. More Capital One interview questions.

6. “How many basketball[s] can you fit in this room” – view answers
Asked at Google. More Google interview questions.

7. “Out of 25 horses, pick the fastest 3 horses. In each race, only 5 horses can run at the same time. What is the minimum number of races required?” – view answers
Asked at Bloomberg LP. More Bloomberg LP interview questions.

8. “If you could be any superhero, who would it be?” – view answers
Asked at AT&T. More AT&T interview questions.

9. “You have a birthday cake and have exactly 3 slices to cut it into 8 equal pieces. How do you do it?” – view answers
Asked at Blackrock. More Blackrock interview questions.

10. “Given the numbers 1 to 1000, what is the minimum numbers guesses needed to find a specific number if you are given the hint “higher” or “lower” for each guess you make.” – view answers
Asked at Facebook. More Facebook interview questions.

11. “If you had 5,623 participants in a tournament, how many games would need to be played to determine the winner?” – view answers
Asked at Amazon. More Amazon interview questions.

12. “An apple costs 20 cents, an orange costs 40 cents, and a grapefruit costs 60 cents, how much is a pear?” – view answers
Asked at Epic Systems. More Epic Systems interview questions.

13. “There are three boxes, one contains only apples, one contains only oranges, and one contains both apples and oranges. The boxes have been incorrectly labeled such that no label identifies the actual contents of the box it labels. Opening just one box, and without looking in the box, you take out one piece of fruit. By looking at the fruit, how can you immediately label all of the boxes correctly?” – view answers
Asked at Apple. More Apple interview questions.

14. “How many traffic lights in Manhattan?” – view answers
Asked at Argus Information & Advisory Services. More Argus Information & Advisory Services interview questions.

15. “You are in a dark room with no light. You need matching socks for your interview and you have 19 gray socks and 25 black socks. What are the chances you will get a matching pair? “ – view answers
Asked at Eze Castle. More Eze Castle interview questions.

16. “What do wood and alcohol have in common?” – view answers
Asked at Guardsmark. More Guardsmark interview questions.

17. “How do you weigh an elephant without using a weigh machine?” – view answers
Asked at IBM. More IBM interview questions.

18. “You have 8 pennies, 7 weight the same, one weighs less. You also have a judges scale. Find the one that weighs less in less than 3 steps.” – view answers
Asked at Intel. More Intel interview questions.

19. “Why do you think only a small percentage of the population makes over $150K?” – view answers
Asked at New York Life. More New York Life interview questions.

20. “You are in charge of 20 people, organize them to figure out how many bicycles were sold in your area last year.” – view answers
Asked at Schlumberger. More Schlumberger interview questions.

21. “How many bottles of beer are drank in the city over the week.” – view answers
Asked at The Nielsen Company. More The Nielsen Company interview questions.

22. “What’s the square root of 2000?” – view answers
Asked at UBS. More UBS interview questions.

23. “A train leaves San Antonio for Huston at 60mph. Another train leaves Huston for San Antonio at 80mph. Huston and San Antonio are 300 miles apart. If a bird leaves San Antonio at 100mph, and turns around and flies back once it reaches the Huston train, and continues to fly between the two, how far will it have flown when they collide.”- view answers
Asked at USAA. More USAA interview questions.

24. “How are M&M’s made?” – view answers
Asked at US Bank. More US Bank interview questions.

25. “What would you do if you just inherit a pizzeria from your uncle?” – view answers
Asked at Volkswagen. More Volkswagen interview questions.

Got a good response to any of these questions? Make sure to leave your attempt at the answers through the above links.

These are just a handful of the 80,000+ interview questions Glassdoor has collected from job interview candidates through our Interview Reviews. In addition to interview questions for specific job openings at specific companies, Glassdoor collects full reviews on the interview process (phone, in-person, panel, etc.) as well as overall difficulty and whether the experience was generally positive, negative or neutral. Our goal is to help job candidates get as prepared as possible for the job interview and it seems to be working – more than half of job candidates who complete an interview review report they got a job offer.