Astrofisika

"Apakah ada kehidupan lain selain di bumi kita yang biru ini? Ataukah Kita hanya sendirian di Luasnya Alam Raya Ini?"

 ~Arip~

Frontiers and Controversies in Astrophysics 

 

 

Lecture 17 - Hubble's Law and the Big Bang (cont.)

Overview:

 

 

Class begins with a review of magnitudes and the problem set involving magnitude equations. Implications of the Hubble Law and Hubble Diagram are discussed. Professor Bailyn elaborates on the Big Bang theory of cosmology and addresses controversial questions related to the age, development, and boundaries of the universe. The fate of the universe, and possibly its end (known as the Big Crunch) are addressed. Imagining an expanding three-dimensional universe is proposed. The lecture ends with a question-and-answer session during which students inquire about a variety of topics related to cosmology, such as the center of the universe, its current expansion, and hypothetical collapse.

Problem sets/Reading assignment:

None assigned

Course Media

Transcript

html

Audio

mp3

Low Bandwidth Video

mov [100MB]

High Bandwidth Video

mov [500MB]

Resources:

Class Notes - Lecture 17 [PDF]

Sumber:

1. The University of Yale Open Course Ware

2. Professor Bailyn Websites

http://www.astro.yale.edu/bailyn/
http://www.astro.yale.edu/


Ucapan Terima Kasih:

1. Bapak. Prof. Dr. Ing. H. B. J. Habibie.

2. Departemen Pendidikan Nasional

3. Kementrian Riset dan Teknologi

4. Lembaga Penerbangan dan Antariksa Nasional


Disusun Ulang Oleh:

Arip Nurahman

Department of Physics, Indonesia University of Education

&

Follower Open Course Ware at MIT-Harvard University, Cambridge.USA.

Semoga Bermanfaat dan Terima Kasih

Astrofisika

"Mencoba memahami alam raya, mempelajari ayat-ayat semesta untuk mencari Kebesaran Yang Maha Pencipta "

~Arip~ 

Frontiers and Controversies in Astrophysics

Lecture 16 - Hubble's Law and the Big Bang

Overview:

The third and final part of the course begins, consisting of a series of lectures on cosmology. A brief history of how cosmology developed into a scientific subject is offered. The discovery of dark energy, along with dark matter, played a crucial role in the development of cosmology. The lecture then discusses the discovery of spiral nebulae in 1920, as well as the "Great Debate" over what they were. Hubble's famous redshift diagram is presented as the basis for Hubble's Constant and Big Bang cosmology. The difficulty of measuring distance of objects in space, and how to do it using the parallax method and the standard candle method, are discussed. Measure brightness using the magnitude scale is explained. Class ends with a review of logarithms.

Problem sets/Reading assignment:

None assigned

Course Media

Transcript

html

Audio

mp3

Low Bandwidth Video

mov [100MB]

High Bandwidth Video

mov [500MB]

Resources:

Class Notes - Lecture 16 [PDF]

Sumber:

1. The University of Yale Open Course Ware

2.  Professor Bailyn Websites

http://www.astro.yale.edu/bailyn/
http://www.astro.yale.edu/


Ucapan Terima Kasih:

1. Bapak. Prof. Dr. Ing. H. B. J. Habibie.

2. Departemen Pendidikan Nasional

3. Kementrian Riset dan Teknologi

4. Lembaga Penerbangan dan Antariksa Nasional


Disusun Ulang Oleh:

Arip Nurahman

Department of Physics, Indonesia University of Education

&

Follower Open Course Ware at MIT-Harvard University, Cambridge.USA.

Semoga Bermanfaat dan Terima Kasih

Indonesian Space Force Command

Indonesian Space Force Command   

 Komando Untuk Keamanan Luar Angkasa 

Dari Angkatan Antariksa Indonesia

"Kami Menjelajahi Alam Raya untuk Menemukan Keagungan Sang Maha Kuasa"

 ~Gen. Arip Nurahman~

 

 

 

(Komando Pasukan Khusus Angkatan Antariksa Indonesia)

 

(Korps Pasukan Khas Angkatan Udara)

 

Jet-powered fighters

It has become common in the aviation community to classify jet fighters by "generations" for historical purposes. There are no official definitions of these generations; rather, they represent the notion that there are stages in the development of fighter design approaches, performance capabilities, and technological evolution.

The timeframes associated with each generation are inexact and are only indicative of the period during which their design philosophies and technology employment enjoyed a prevailing influence on fighter design and development. These timeframes also encompass the peak period of service entry for such aircraft.

First generation subsonic jet fighters (mid-1940s to mid-1950s)

Main article: First generation jet fighter

Messerschmitt Me 262A at the National Museum of the United States Air Force

The first generation of jet fighters comprises the initial, subsonic jet fighter designs introduced late in World War II and in the early post-war period. They differed little from their piston-engined counterparts in appearance, and many employed unswept wings. Guns remained the principal armament. The impetus for the development of turbojet-powered aircraft was to obtain a decisive advantage in maximum speed. Top speeds for fighters rose steadily throughout World War II as more powerful piston engines were developed, and had begun approaching the transonic flight regime where the efficiency of piston-driven propellers drops off considerably.

RAF Gloster Meteor

The first jets were developed during World War II and saw combat in the last two years of the war. Messerschmitt developed the first operational jet fighter, the Me 262. It was considerably faster than contemporary piston-driven aircraft, and in the hands of a competent pilot, was quite difficult for Allied pilots to defeat. The design was never deployed in numbers sufficient to stop the Allied air campaign, and a combination of fuel shortages, pilot losses, and technical difficulties with the engines kept the number of sorties low.

Nevertheless, the Me 262 indicated the obsolescence of piston-driven aircraft. Spurred by reports of the German jets, Britain's Gloster Meteor entered production soon after and the two entered service around the same time in 1944. Meteors were commonly used to intercept the V-1 "buzz bomb", as they were faster than available piston-engined fighters. By the end of the war almost all work on piston-powered fighters had ended. A few designs combining piston and jet engines for propulsion – such as the Ryan FR Fireball – saw brief use, but by the end of the 1940s virtually all new combat aircraft were jet-powered.

Despite their advantages, the early jet fighters were far from perfect, particularly in the opening years of the generation. Their operational lifespans could be measured primarily in hours; the engines themselves were fragile and bulky, and power could be adjusted only slowly. Many squadrons of piston-engined fighters were retained until the early-to-mid 1950s, even in the air forces of the major powers (though the types retained were the best of the World War II designs). Innovations including ejector seats and all-moving tailplanes were introduced in this period.

The Americans were one of the first to begin using jet fighters post-war. The Lockheed P-80 Shooting Star (soon re-designated F-80) was less elegant than the swept-wing Me 262, but had a cruise speed (660 km/h [410 mph]) as high as the combat maximum of many piston-engined fighters. The British designed several new jets, including the iconic de Havilland Vampire which was sold to the air forces of many nations.

F-86 Sabres

The British transferred the technology of the Rolls-Royce Nene jet engine technology to the Soviets, who soon put it to use in their advanced Mikoyan-Gurevich MiG-15 fighters which were the first to introduce swept wings in combat, an innovation first proposed by German research which allowed flying much closer to the speed of sound than straight-winged designs such as the F-80. Their top speed of 1,075 km/h (668 mph) proved quite a shock to the American F-80 pilots who encountered them over Korea, along with their armament of two 23 mm cannons and a single 37 mm cannon compared to machine guns. Nevertheless, in the first jet-versus-jet dogfight in history, which occurred during the Korean War on 8 November 1950, an F-80 (as the P-80 had been redesignated) intercepted two North Korean MiG-15s near the Yalu River and shot them down.

The Americans responded by rushing their own swept-wing F-86 squadrons to battle against the MiGs which had similar trans-sonic performance. The two aircraft had different strengths, but were similar enough that the superior technology such as a radar ranging gunsight and skills of the veteran United States Air Force pilots allowed them to prevail.

The world's navies also transitioned to jets during this period, despite the need for catapult-launching of the new aircraft. Grumman's F9F Panther was adopted by the U.S. Navy as their primary jet fighter in the Korean War period, and it was one of the first jet fighters to employ an afterburner. The de Havilland Sea Vampire was the Royal Navy's first jet fighter. Radar was used on specialized night fighters such as the F3D Skyknight which also downed MiGs over Korea, and later fitted to the F2H Banshee and swept wing F7U Cutlass and F3H Demon as all-weather / night fighters. Early versions of Infra-red (IR) air-to-air missiles (AAMs) such as the AIM-9 Sidewinder and radar guided missiles such as the AIM-7 Sparrow which would be developed into the 21st century were first introduced on swept wing subsonic Demon and Cutlass naval fighters.

See also: List of first generation jet fighters

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Tentara Nasional Indonesia Angkatan Darat (Indonesian Army)
 

 http://www.tniad.mil.id/

Tentara Nasional Indonesia Angkatan Laut (Indonesian Navy)

http://www.tnial.mil.id/

Tentara Nasional Indonesia Angkatan Udara (Indonesian Air Force)

 http://tni-au.mil.id/

Kepolisian Negara Republik Indonesia (Indonesian Police)

 

http://www.polri.go.id/

Sumber: Wikipedia