GGRB05H3 Lecture Notes - Lecture 2: Northeast Megalopolis, Economic Globalization, Creative Destruction

46 views7 pages

purpledog224

14 Oct 2012

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Early urban settlements: middle east cradle of civilization , generally quite small cities, initially tens of thousands of people and later on hundreds of thousands (small by todays standards but pretty big at the time) How do we understand the growth of cities. Urbanization in this definition is about people, increasing density or sprawl. Counterurbanization there are cities that are not growing anymore, they are experiencing and managing a decline in growth. Reurbanization the inside of the city starts to grow again and people start to move back to the core of the city. Urban to urban (intra national); people who move from city to city. Urban geographers became fascinated by urban structure and why certain structures where placed in certain places information. Tried to map activities within cities using census data and other: wanted to come up with a model of how contemporary cities grew. Chicago was the hotbed for models of urban growth.

Related Questions

This applet shows six disks rotating with constant angular acceleration. No two have the same initial angular velocity and angular acceleration. To answer the following questions, number the disks starting from the top. That is, call the yellow disk "1" and go sequentially down to the red disk, which will be "6". In the following questions, you will be asked to determine whether the disks' angular velocities and accelerations are positive, negative, or zero. Keep in mind that angular velocity is considered positive if rotation is in the counterclockwise direction. Angular acceleration is positive if the rotation is in the counterclockwise (positive) direction and the angular speed is increasing, or if rotation is the clockwise (negative) direction and the angular speed is decreasing (thus the angular velocity is becoming less negative). Negative angular acceleration is defined analogously.

http://session.masteringphysics.com/probhtml/ActivePhysics/pt1a/Media/RotMotionStatics/RotationalKinematics/Sim4.html

Part A

Which of the disks have positive initial angular velocity?

Write down the numbers, in order, that corresponds to the disk(s)

Part B

Which of the disks have negative initial angular velocity?

Write down the numbers, in order, that corresponds to the disk(s)

Part C

Which of the disks have zero angular acceleration?

Write down the numbers, in order, that corresponds to the disk(s)

Part D

Which of the disks have positive angular acceleration?

Write down the numbers, in order, that corresponds to the disk(s)

apricotclam488

1. The Jeans instability occurs when
Athe pressure in a gascloud is less than its gravitationalforce.
Bthe pressure in a gascloud is greater than its gravitationalforce.
Cthe temperature in acollapsing cloud is hot enough to fuseHydrogen.
Dthe temperature in acollapsing cloud is hot enough to fuse Helium.

2. At what stage in its life does a star pass through theprotostarphase?
AAfter condensationbut before nuclear reactions begin in itscore.
BWhile it is convertinghydrogen into helium in its core.
CAfter nuclear reactionsend in its core, but before the red giantphase.
DWhen it is expanding insize as a red giant or supergiant.

3. The characteristics of an open cluster of stars are
Aa few hundredmembers, often very young and still embedded in thegas and dustfrom which they were formed.
Bmany thousand members, ofdifferent ages.
Ca few dozen members, theremnant of a globular cluster of starsfrom which most of themembers have escaped.
Dhundreds of thousands ofmembers, all very old, and no or verylittle interstellar gas anddust.

4. What is a protostar?
AA star near the endof its life, before it explodes as asupernova.
BA sphere of gas aftercollapse from an interstellar cloud butbefore nuclear reactionshave begun.
CA small interstellarcloud, before it collapses to become astar.
DA shell of gas left behindfrom the explosion of a star as asupernova.

5. What is an H II region?
AA region of hot,ionized hydrogen around one or more O and Bstars.
BA region of molecularhydrogen inside a giant molecularcloud.
CA region of neutral,atomic hydrogen in interstellar space.
DA region of gas and dustformed by the explosion of a massive star.

6. The total time that the Sun will spend as a main sequencestaris
Aabout 4.5 millionyears.
Bat least 200 billion yearsyears.
Cabout 1 millionyears.
Dabout 10 billionyears.

7. How is a star's lifetime related to its mass?
AThe lifetimes ofstars are too long to measure, so it is not knownhow (or if) theirlifetimes depend on mass.
BA star's lifetime does notdepend on its mass.
CLower-mass stars runthrough their lives faster and have shorterlifetimes.
DHigher-mass stars runthrough their lives faster and have shorterlifetimes.

8. In the Hertzsprung-Russell diagram, how does the position ofatypical star change while it is at the main sequence phase ofitsevolution?
AA star's position onthe main sequence is determined only by itsmass and not its age,and so, stars do not move along the mainsequence duringevolution.
BMassive stars (4 solarmasses) move toward the upper left as theirluminosity increases,while lower-mass stars move toward the lowerright as theirtemperature decreases.
CStars move from upperright to lower left while they are on themain sequence.
DStars move from upper leftto lower right while they are on themain sequence.

9. Why does the core of the Sun contain more helium andlesshydrogen than does the surface of the Sun?
AHelium condenses moreeasily so, when the Sun was forming the corebecame helium-rich;vast quantities of hydrogen were added onlyafter the core becamemassive enough.
BThe hydrogen has beenlifted out of the core by the Sun's magneticfield.
CHelium is heavier thanhydrogen, and has sunk toward the center ina process of chemicaldifferentiation.
DThermonuclear reactionshave converted much of the originalhydrogen in the core intohelium.

10. In terms of nuclear reactions, what is the next stage ofastar's life after the end of hydrogen burning in thecore?
AHydrogen burning ina thin shell around the core.
BHelium burning in thecore.
CCarbon burning.
DDeath (it becomes eithera supernova or a white dwarf).

Astrophysicists in the 1960s tried to explain the existence and thestructure of pulsars â extremely regular astronomical sources ofradio pulses whose periods ranged from seconds to milliseconds. Atone point, these radio sources were given the acronym LGM, standingfor âLittle Green Men,â a reference to the idea that they might besignals of extraterrestrial civilizations. The explanation giventoday is no less interesting. Consider the following. Our Sun,which is a fairly typical star, has a mass of 1.99x10^30 kg and aradius of 6.69x10^8 m. Although it does not rotate uniformly,because it isnât a solid body, its average rate of rotation isabout 1 rev / 25 days. Stars larger than the sun can end theirlives in spectacular explosions called supernovae, leaving behindcollapsed remnants of the stars called neutron stars. Neutron starshave masses comparable to the original masses of the stars, butradii of only a few kilometers. These stars emit beams of radiowaves. Because of the rapid angular speed of the stars, the beamssweep past Earth at regular, very short, intervals. To produce theobserved radio-wave pulses, the star has to rotate at rates fromabout 1 rev/s to 1000 rev/s.

a. Estimate the rotation rate of the Sun if it were to collapseinto a neutron star of radius 10 km. The Sun is not a uniformsphere of gas, and its moment of inertia is given by I = 0.059MR2.Assume that the neutron star is spherical and has a uniform massdistribution.
b. Is the rotational kinetic energy of our Sun greater of smallerafter the collapse? By what factor does it change, and where doesthe energy go to or come from?

GGRB05H3 Lecture Notes - Lecture 2: Northeast Megalopolis, Economic Globalization, Creative Destruction

Document Summary

Get access

Related Documents

GGRB05H3 Study Guide - Final Guide: Hoodie, Cash Flow, Air Miles

GEOG 1HB3 Chapter Notes - Chapter 11: Aspero, Urban Sprawl, Megacity

Geography 1400F/G Lecture Notes - Lecture 9: Epidemiological Transition, Asia-Pacific, Informal Sector

Related Questions