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Solved: Bam!—Apollo 15 Lands on the MoonThe first word

Physics with MasteringPhysics | 4th Edition | ISBN: 9780321541635 | Authors: James S. Walker ISBN: 9780321541635 54

Solution for problem 124PP Chapter 2

Physics with MasteringPhysics | 4th Edition

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Physics with MasteringPhysics | 4th Edition | ISBN: 9780321541635 | Authors: James S. Walker

Physics with MasteringPhysics | 4th Edition

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Problem 124PP

Problem 124PP

Bam!—Apollo 15 Lands on the Moon

The first word spoken on the surface of the Moon after Apollo 15 landed on July 30,1971, was “Bam!” This was James Irwin’s involuntary reaction to their rather bone-jarring touchdown. “We did hit harder than any of the other flights!” says Irwin. “And I was startled, obviously, when I said, “Bam!’˝

The reason for the “firm touchdown” of Apollo 15, as pilot David Scott later characterized it, was that the rocket engine was shut off a bit earlier than planned, when the lander was still 4.30 ft above the lunar surface and moving downward with a speed of 0.500 ft/s. From that point on the lander descended in lunar free fall, with an acceleration of 1.62 m/s2. As a result, the landing speed of Apollo 15 was by far the largest of any of the Apollo missions. In comparison, Neil Armstrong’s landing speed on Apollo 11 was the lowest at 1.7 ft/s—he didn’t shut off the engine until the footpads were actually on the surface. Apollos 12, 14, and 17 all landed with speeds between 3.0 and 3.5 ft/s.

To better understand the descent of Apollo 15, we show its trajectory during the final stages of landing in Figure 2-37 (a). In Figure 2-37 (b) we show a variety of speed-versus-time plots.


Which of the speed-versus-time plots in Figure 2-37 (b) correctly represents the speed of the Apollo 15 lander?


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Streckfuss Amy Brogan March 29 & 31, 2016 The Cold War (Part 1) 1945-1950 1870: Germany had just unified; prior Germany was a collection of 28 separate jurisdictions. They set off immediately to attack France to announce their intent to be a powerful country in Europe. The Multicentric World Power Model was developed as of the beginning of the 20 century with the powers of England, France, Russia, Ottoman Empire, Austria-Hungary, and America among others. At the end of World War I, the Ottoman Empire and Austria-Hungary were completely obliterated, and others were weakened. WWII further hones this and England is ended as a world power by the end of the war. The United states and the Soviet Union are the only two powers remaining, a bi-polar power model.  Agenda o Legacy of War o Role of Military/Services  Navy and Airforce were equal o NSA ‘47  Gave Secretary of War a seat in the Cabinet  Gave permanent status to wartime office of strategic services (Central intelligence service) o Rise of SAC  Airforce was really ahead of the Navy o Mr X and NSC 68  NSC 68: nation security council paper  Cod name for George Kennan  Containment o George Kennan  Deputy head of Mission USSR o 6000-word Telegram – “Long Telegram” / Foreign Affairs (1946) by “Mr. X”  playbook for the Cold War, outlined “Russia’s aggressive tendencies” and submitted containment policies o Options: could come to peaceful agreement or we could blow them off the earth (war)  Kennan’s offered third option: simply contain Russians were they were. Stifle their world domination tendencies  NSC-68 – 14 April 1950 o Position paper by Paul Nitze and others about Kennan’s proposition managing the budget of putting the idea through  Recommended a massive buildup of an increase in funding for the armed forces in an effort to contain the Soviets o Based on the assumption that Soviet Union had a systematic strategy aimed at the spread of Communism around the world o President Truman signed it in August  Shaping the Pot War World o Yalta Conference (Feb 4-11, 1945)  President died 2 months later, he was called weak and sick as an explanation for his inability to stand up to Stalin o Potsdam Conference  July 17-August 2, 1945  Truman comes away with the idea that he will have to be tougher with Stalin o Both meetings for peace because war is almost over, to outline what happens after war is over o Race to Berlin  After the war, Germany is divided by where the armies of the remaining world powers end up.  Berlin divided in roughly the same lines o Korea also dived in similar fashion th  38 parallel is the divide between North and South  Truman’s Perspective o “Russians [are] as untrustworthy as Hitler and Al Capone.” o “…They need to be taught how to behave in the civilized world.” o Assumed the soviets were intent on world domination  Hitler had been interested in the same thing  Truman had no intent in allowing the soviets to achieve this  We were brimming with confidence because we were the only power on earth with the Atomic bomb  Stalin’s Goals o “…security for himself, his regime, his country, and his ideology, in precisely that order. He sought to make sure no international challenged could ever again endanger his personal rule and that not external threats would ever again place his country at risk.” – John Lewis Gaddis o Key: security  We thought they wanted world domination, what they did want was border security. They had been invaded twice in the last century (Napoleon and Hitler) and had inflicted catastrophic damage on the population. Stalin had no intent to let this happen again.  Control of eastern Germany, Poland, Czechoslovakia, and etc., was protection so attacking armies had to move through eastern Europe before making it to Russia o Gaddis: leading cold war historian, dozen books on the cold war, used to teach at Ohio university (state government started cutting higher ed funding and Gaddis moved to Yale)  Purpose of the Military o “Thus far the chief purpose of our military establishment has been to win wars. From now on its chief purpose must be to avert them.”  Bernard Brodie, The Absolute Weapon, 1946 o Brodie- nuclear strategist – future war would begin with conventional weapons and would only escalate if nuclear war was unavoidable o Later believed we should go nuclear right away to make sure no war took place o Long term aspect: constituted fundamental shift in military policy  Used to downsize and demobilize  Now we don’t; downsize, we increase size of military, especially the budget (nuclear and development is expensive)  G.I. Bill – education and funding for former soldiers from defense department, campuses around the country expanded because of this  A military revolution o Coined in the 50’s (actually about Sweden, we adopted gunpowder) – changes in the military and in military tactics forced changes in governments  Government tailored around military advances, the military is leading the way in society  Myth: Eisenhower built the interstate highway so the military could move around; actually built so everyone could move around. But should the need arise, they would be helpful.  G.I. Bill: education through the military. Long term effect: we created a culture of expectation for their kids and so on to go to college. Earlier generations considered themselves lucky to get through high school. Educated population to be ahead of the Russians.  GPS – crated for the military, no we all use it. Arial reconnaissance leads to GPS and leads to traffic report from helicopter journalists  Large navy made world domination/world power possible – “The Importance of Sea Power”  Atomic Military Revolution o Where does the army fit in  Weren’t going to need boots on the ground o What does future conflict look like  Looked like war was going to be fought and won quickly o Where do we put our defense dollars  In the air force, late 40’s early 50’s o Culture  Comic strips, toys, drinks  The New Structure of our Military o Unification Debates o National Security Act of 1947  The generals of the newly formed air force propounded a new doctrine: that strategic bombing, particularly with nuclear weapons, was the sole decisive element necessary to win any future war; a d was therefore the sole means necessary to deter an adversary from launching a Pearl Harbor-like surprise attack or war against the United States. o Did WWII prove to be a strategic bombing theorist example  Yes: Atomic bombs dropped and Japanese quit  But already after a long and life-heavy war  No: Bombing of Germany and Britain only made the people want to fight back more. Small bombings not the knock-out bombing to make the war end like the atomic bombs o Get rid of the army and give all funding to atomic bomb  No: if no army then all skirmishes will be at an atomic battle because there won’t be anybody to fight the small battles  Can’t nuke Moscow for every small battle, maybe for larger issues  1949: Russians have atomic bombs  Cheaper in 1920’s to fund air force than others  Spending 5 billion dollars to make bomb and plane and it is no longer cheaper  New argument: spend it here to make war quick vs. not and losing a war to the Russians (All dead, or all turned into communists)  Cheaper in lives  Until Russians got the bomb too  Strategic Air command: the only thing that could deter the Russians from starting a war in the first place  Now: Army so big and impressive so that no one will attack us just by our image of force  Revolt of the Admirals o “There’s no reason for having a Navy and Marine Corps. General Bradley tells me that amphibious operations are a thing of the pas. We’ll never have any more amphibious operations. That does away with the Marine Corps. And the Air Force can do anything the Navy can do nowadays, so that does away with the Navy.” – Secretary of defense Louis A. Johnson (December 1949)  Top civilian cabinet member quoting top military officer o Reaction to cancelation of new aircraft carrier in the budget, money instead when into the air force.  Not about just one carrier, it’s about the replacement of the navy with the air force, scrapping the carriers scraps “all of us” at once o B-36 Controversy  B-36 proposed continent bomber; the navy opposed its construction o USS United States o Morality of Strategic bombing  Possible that was not what the admirals were really worried about; they were more worried about losing their funding  US Airpower o “For good or ill, air mastery is today the supreme expression of military power and fleets and armies, however necessary, must accept a subordinate rank.” - Churchill  The Importance of Ground Forces o You may fly over a land forever; you may bomb it, atomize it, pulverize it and wipe it clean of life – but if you desire to defend it, protect it and keep it for civilization, you must do this on the ground, the way the Roma legions did, by putting young men into the mud.” – T.R. Fehrenbach, This Kind of War  Berlin Airlift 1948 o Russians cut of Allied roads into Berlin so they couldn’t give supplies to the trapped people o Allies toyed with the idea of attacking Russia then o Instead they airlifted food and supplies into Berlin for almost a year before the Russians re-opened land access  Considered a public relations victory  One of the crews started taking in goodie boxes into Germany for the kids and the press liked it, so everyone started doing it. They focused on the children and the cruelty of the Russians of taking away joy from hem  Fall 1949 o 3 September - WB-29 finds nuclear material  WB-29 = weather reconnaissance flight o 25 September – Truman announces Soviet atomic bomb o 1 October – PRC formally established o 5 October – “super bomb” (fusion) bomb discussions begin o 13 October – CNO Denfeild’s testimony to SASC  Denfeild lost his job for arguing against the air force too strongly o 17 October – Truman approves the enlargement of the nuclear stockpile  The Cold War 1954-1989 o Cuban revolution (Castro) o Launch of Sputnik o Reagan resides over the end of the Cold War  Key Themes o Role of Technology o US Policy and patterns of Cold War o Evolution of US Nuclear Strategy o Effects of conflict on American Society o Implications for US Army  Periods o The Global Confrontation 1950-1960  Dulles Massive Retaliation Speech – 12 January 1954: ability to launch a second strike, even if the Soviet wipe out all the major cities, members need to still be able to launch the bombers - Mutually insured destruction (we can still bomb you even if you take us out)  Geneva Conference Final Declaration – July 1954  SEATO – 8 September 1954  Warsaw Pact – 14 May 1955  Peaceful Coexistence – 14 February 1956  Hungarian Revolution – October -November 1956  Suez Crisis – July-November 1956  Cuban Revolution – 1 January 1959  U-2 Affair – 1 May 1960 o Crisis and Conflict 1961-1969  Berlin Crisis – Summer 1961  Cuban missile crisis – October 1962– closest we ever came to war. Both sides learned just how far they could push the other before hitting the button and how to avoid these things  Sino-Soviet Split – 1960 -1963  Nuclear Test Ban Treaty – August 1963  Vietnam – 1961-1968  Nuclear Non-proliferation Treaty – July 1968  Invasion of Czechoslovakia – August 1968  Brezhnev Doctrine – Fall 1968 o Era of Détente 1969-1979  Nixon Doctrine – Summer-Fall 1969  Nixon’s visit to China – February 1972  Strategic Arms Talks (SALT) AND Anti-Ballistic Missile Treaty – May 1972  Helsinki Act – August 1975  Normalization of US-China Relations – 1973-1976  SALT II Agreement – June 1979 o The Cold war was a nuanced conflict, viewed from multiple angels. Military cold war, economic cold war, religious, social, and cultural cold war.  Economic: Gattis argues that the Cold War was really won in 1952 because we won it economically with the Marshal plan and by rebuilding eastern Europe. When the world looked at the comparison between capitalism and communism (good German cars and bad cardboard-lined cars), the battle was done.  The Religious Cold War was marked by high church attendance in the states, “One Nation Under God” added to the Pledge of Allegiance further showing the better side vs. the communist side which was closing down churches  Socio-cultural: WWII started unions and they gave “no strike pledges” during the war, benefits continued through after the war. This showed what was possible under capitalism vs. communism (taking shots at the government).  Race relations: 1954 supreme court with Brown vs. Board of Education (segregates schools), argued that this was a Cold War ploy to sow that arguments could be solved peacefully. Also free-speech movement, Rock-N-Roll, vs. highly regimented life behind the Iron Curtain  Technologically: none more symbolically important than space race. Bormann (early astronaut) many people thought it was about moon rocks, none were worried about the rocks, they were worried about beating the Soviets.  Proxy Wars: Korea and Vietnam o The Denouement of the Cold War 1980-1989  Carter Doctrine – January 1980  Polish Imposition of Marshal Law – December 1981  Reagan’s SDI Speech – March 1983  Geneva Summit – November 1985  Reykjavik Summit – October 1986  INF Treaty – December 1987  Soviet Union leaves Afghanistan – February 1989  Opening of the Berlin Wall – November 1989  German Unification – July 1990  Division of Europe 1950-1991  NATO – created to give us options. The immediate focus after the war was thee air force (creation atomic strike force, but that limits options of attack). Return of convention ground forces to Europe and less-deadly options  Warsaw Pact: Russian Pact  Pattern of the Cold War o Action – Reaction o Policy – Counter Polity o COMECON – committee for economic assistance – Russian version of Marshal plan, not nearly as successful o NATO – Warsaw Pact (1953) o Both superpowers prepared nuclear arsenal as a determent  Soviet Atomic Bomb (1949)  US Hydrogen Bomb (1951)  Soviet Hydrogen Bomb (1953)  The Triad:  ICBMs: Intercontinental ballistic missile  Ballistic Missile submarines  Long range bombers  Large mechanized land forces o NCS 162/2 (1953) Nuclear weapons accepted as conventions arms o From this point forward, the weapons technically available for use in any type of conflict o 1954 – Secretary of State Dulles promised “massive retaliation” in response to Soviet aggression.  Evolution of US Nuclear Strategy o 1954-1956 Massive Retaliation o 1962-1968 Flexible response  Assured destruction  Mutual assured destruction o 1968-1976 Limited Nuclear Options o 1977-1980 Counterveiling/Decapitation o 1981-1990 Counterforce/Strategic Defense  Implications for US Army o In early 1950’s, questions about viability of conventional land forces o The Potomac Division  To better organize for possible atomic war, Army adopted Potomac division. Large rifle companies and appropriate artillery and support field units. Self- sustaining. Used till the 60’s o Emergence of Counter-Insurgency Mission o Emergence of Idea of Limited War o Atomic technological advances: nuclear powers weren’t just for the air force; navy gets submarines with atomic missiles  Cold War and American Society – broader cultural fears o Cold War affected American attitudes about larger world o Environment often led to fear and paranoia o Sen. Joseph McCarthy and House Committee on Un-American Activities (HUAC) – 1947- 1954 – Committee tried to root out real and perceived communists in Hollywood, US Dept. of State, and US Army  Tail-gunner Joe – McCarthy was really a desk jockey, but he claimed fighting out in the fray, told you anything you wanted to hear to get your vote. McCarthy hearing destroyed lives and careers by accusing them of being communists  Hollywood target of traditional congress. Cold War witch hunt lead to Hollywood blacklist, artists’ careers destroyed or severely interrupted by accusations saying they had communist pasts  “The Front” - Woody Allen film about blacklisted writers o Bunkers/backyard bomb shelters, duck and cover practices at schools  Korea – Proxy War o Couldn’t afford to confront Russian face-on, so the idea of a limited war/proxy war, removed from both countries territories we couldn’t be hurt directly. o Background – Old unified state since 7 century  Proved tempting target for the Japanese during WWII, and occupied Korea from 1910 to 1945  Civil war elements between north and south left over from WWII  Army of South Korea largely composed of Koreans who collaborated with the Japanese during occupation  Army of North Korea leaders had previously fought as guerillas against the Japanese  Split Korea same way Europe was split  Soviet Union occupied Korea north of the 38 parallel and United States occupied south of the line  Soviet imposed a communist government o Democratic People’s Republic of Korea (DPRK) o Lead by Kim Il Sung o Pyongyang as capital  The United States put in place a nationalist/capitalist democracy o Republic of Korea (ROK) o Led by Syngman Rhee o Seoul as capital o Original intent was to put the country back together, to reunify and then get out, this didn’t work out  US reduced its troop levels in SK to 500 troops by June 1949  Joseph Stalin (Of Russia) concluded that the US would not be willing to fight to defend South Korea  January 30, 1950 – Stain via telegram notified Kim Il Sung that he was willing to help Korea unify as a communist state o Tensions/ US Involvement  Political tensions building during 1940’s  South Korea was unstable economically, they needed help to build a military  US feared that South Korea would fall to communism  US Government Helped to Build up the South Korean Military  Both the US and the Soviets removed their troops from Korea in 1949 o Fighting Begins  Test of new UN (purpose was to provide collective security), first involved by calling a ceasefire. UN consists of two bodies, general assembly (everybody is a member) real power in security council (15 member countries, 10 serve one year terms, 5 permanent members made of countries who won WWII + Nationalist Chinese and Russians).  ’49 Mao had run Chiang Kai-Shek out of China. Who should be the China seat New Mao or nationalist government in Taiwan. They argue that Mao staged a Coup d'état, and UN refused to recognize Mao’s government. In response, the Soviets are boycotting the UN at the time of the invasion. Each of the 5 seats has veto power, discussions of sending a peace treaty and resolution 82 passed because Russians could not veto. UN goes to war in Korea  South collapses quickly o North Korea Attacks  June 25, 1950 – North Korea attacks South Korea  June 28, 1950 – The capital of Seoul had fallen, the ROK army was in disarray  The UN became involved and called for an immediate ceasefire  Because the Soviets were boycotting the UN (because the UN refused to acknowledge Mao’s rule of China) they could not veto the vote to send a peace treaty (Resolution 82)  21 of the UN member states agreed to contribute arms, money, and/or troops to rid South Korea of its North Korean aggressor o Support for South Korea  US sponsored the resolution that North Korea was the aggressor  US Forces entered South Korea under the direction of General McArthur  MacArthur returns to states for 1 time in 15 years since WWII, possible factor in troubles with Truman. MacArthur treated in Eurasia as a replacement emperor, may have gone to his head  15 other countries gave military and monetary support; however, no other country gave the same support that the US did. o US Forces  Gen Douglas MacArthur was placed in command of the UN forces, which included combat and medical units from 22 countries  The US provided 50% of ground forces, 86% of naval forces, and 93% of the air power for the UN forces. (South Korea provided most of the remainder) o Pusan Perimeter – grisliest fighting of the war, goes on till September and we suffer more than 4000 dead and over 400 POW, situation becomes hot, defending general Walker issues an order “The will be no retreat.” Similar to Haig’s speech in WWI “With our backs to the wall … must fight on till the end.”  Walking Line: thin defense in front, stronger line in the back, dismissed as being too risky o Inchon – amphibious launch by McArthur, changed course of the war, cut off North Korean supply line, our troops and ROK break out of perimeter and pursue fleeing North Korean troops. Seoul is recovered within days, cutting the North Korean supply line. o Korean War  On to the Yalu – Sept-Nov, 1950 – ground forces didn’t cross the river, but the air force did on a regular business  Capitalizing on Secretary of Defense George Marshall’s directions (“We want you to feel unhampered tactically and strategically to proceed north of the 38 parallel…”) MacArthur pushed UN forces north towards the Yalu River  Ignoring evidence that Chinese forces had moved across the Yalu River into North Korea, MacArthur assured US troops they would be “home by Christmas”  MacArthur further risked forces by splitting his troops o X Corps advancing along the eastern coast o Eighth Army advancing along the western coast  Chinese Intervention – 26 Nov 1950 – UN starts to lose ground when China joins war until they relaunch.  Relief of MacArthur – 11 April 1951 – McArthur is finally canned for being blatantly insubordinate around Truman to congress Truman goes to pacific to meet McArthur, general is supposed to be waiting on the tarmac to give the salute, but instead he had his radar people tell him when plane was about to land and took off in his own. Both circled the tarmac till McArthur’s pilot ordered to the ground. Tremendously popular in States, Truman’s popularity was on the decline as consequence.  UN Counteroffensive – Spring 1951  Negotiations and Stalemate – 1951-1953  Directive to the Commander of the United Nations Forces in Korea  “Your military objective is the destruction of North Korean armed forces. In obtaining this... you are authorized to conduct military operations… north of the 38 parallel… provided that at the time of such operation there has been no entry into North Korea by major Soviet or Chinese Communist forces, no announcement of intended entry, nor threat to counter our operations militarily in North Korea.”  China’s Involvement  China aided North Korea in late November  Due to China’s involvement, MacArthur called for a major expansion of the war. His proposal included: o Blockading China’s coast o Invading the interior of China  Solid support for driving North Koreans out of the south, but taking on the Chinese was another matter entirely  Conflict regarding the plan – could escalate into a world war o Supporters of MacArthur’s plan said it would overthrow the Communist regime in China o Opponents argued that blockading China could entice Soviets to become involved  Chinese Offensive  US forces unexpectedly ran into approximately 180,000 Chinese troops. The right flank of the Eighth Army (US) shattered and the X Corps (US) fought a desperate struggle near the Chosin Reservoir  The UN troops were evacuated back to the Pusan perimeter and Seoul was captured by the Chinese forces  November 28, 1951 – a shaken MacArthur informed the Joint Chiefs of Staff that the UN forces faced an “entirely new war”

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Chapter 2, Problem 124PP is Solved
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Textbook: Physics with MasteringPhysics
Edition: 4
Author: James S. Walker
ISBN: 9780321541635

This textbook survival guide was created for the textbook: Physics with MasteringPhysics, edition: 4. This full solution covers the following key subjects: Apollo, speed, figure, landing, surface. This expansive textbook survival guide covers 32 chapters, and 3833 solutions. Physics with MasteringPhysics was written by and is associated to the ISBN: 9780321541635. The full step-by-step solution to problem: 124PP from chapter: 2 was answered by , our top Physics solution expert on 07/27/17, 10:59AM. Since the solution to 124PP from 2 chapter was answered, more than 410 students have viewed the full step-by-step answer. The answer to “Bam!—Apollo 15 Lands on the MoonThe first word spoken on the surface of the Moon after Apollo 15 landed on July 30,1971, was “Bam!” This was James Irwin’s involuntary reaction to their rather bone-jarring touchdown. “We did hit harder than any of the other flights!” says Irwin. “And I was startled, obviously, when I said, “Bam!’?The reason for the “firm touchdown” of Apollo 15, as pilot David Scott later characterized it, was that the rocket engine was shut off a bit earlier than planned, when the lander was still 4.30 ft above the lunar surface and moving downward with a speed of 0.500 ft/s. From that point on the lander descended in lunar free fall, with an acceleration of 1.62 m/s2. As a result, the landing speed of Apollo 15 was by far the largest of any of the Apollo missions. In comparison, Neil Armstrong’s landing speed on Apollo 11 was the lowest at 1.7 ft/s—he didn’t shut off the engine until the footpads were actually on the surface. Apollos 12, 14, and 17 all landed with speeds between 3.0 and 3.5 ft/s.To better understand the descent of Apollo 15, we show its trajectory during the final stages of landing in Figure 2-37 (a). In Figure 2-37 (b) we show a variety of speed-versus-time plots.FIGURE 2-37 Which of the speed-versus-time plots in Figure 2-37 (b) correctly represents the speed of the Apollo 15 lander?A B C D” is broken down into a number of easy to follow steps, and 237 words.

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Solved: Bam!—Apollo 15 Lands on the MoonThe first word