Astronomy quiz question: neutron star in binary star system

Astronomy 210 Quiz 5, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

A compact object with __________ may be evidence of a neutron star in a binary system.
(A) a hot, x-ray emitting accretion disk.
(B) regularly timed x-ray pulses.
(C) zero mass and no emitted light.
(D) repeated nova bursts.

Correct answer: (B)

Response (B) is evidence of a neutron star (pulsar) in a binary system; response (D) is evidence of a white dwarf in a binary system. Response (C) is not true for black holes (which have a finite mass, but zero size, and emit light from their accretion disks). Note that response (A) is also evidence of white dwarfs and black holes in binary systems, as they also have accretion disks.

Section 70158
(A) : 15 students
(B) : 24 students
(C) : 2 students
(D) : 3 students

"Success level": 59% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.81

Astronomy quiz question: black hole in binary star system

Astronomy 210 Quiz 5, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

A compact object with __________ may be evidence of a black hole in a binary system.
(A) a hot, x-ray emitting accretion disk.
(B) regularly timed x-ray pulses.
(C) zero mass and no emitted light.
(D) repeated nova bursts.

Correct answer: (A)

Response (B) is evidence of a neutron star (pulsar) in a binary system; response (D) is evidence of a white dwarf in a binary system. Response (C) is not true for black holes (which have a finite mass, but zero size, and emit light from their accretion disks). Note that response (A) is also evidence of white dwarfs and neutron stars in binary systems, as they also have accretion disks.

Section 70160
(A) : 14 students
(B) : 4 students
(C) : 16 students
(D) : 0 students

"Success level": 46% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.78

Online reading assignment question: black hole tags

Astronomy 210, Fall Semester 2009
Cuesta College, San Luis Obispo, CA

091028-blackholetags
http://www.flickr.com/photos/waiferx/4053363307/
Originally uploaded by Waifer X

Wordle.net tag cloud for "black hole" generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA (http://www.wordle.net/show/wrdl/1276159/Untitled).

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

Write down five words that describe or are associated with "black hole." Keep word phrases together with no spaces between them (e.g., "blackhole"). (Graded for completion.)

Student responses
Section 70158

time dense eventhorizon gravity light
deep death powerful crazy destruction
nothing empty black star
supernova x-rayaccretiondisk dense
implode gravity spaghettification mystery timetravel
darkness emptiness force suction mysterious
infinitegravity nolightescapes eatsstars centerofgalaxies totalcollapse
infinitedensity zerovolume singularity eventhorizo 3.0mSun
isaregionofspace
blackhole time space light noreturn
dense wormhole timeless darkness crushing
end demolished finished ruined ice
gravity supernova densemass nonescapinglight colorless
blackhole bottomlesspit mysterious crappy timeportalperhaps
collapes gases escape dark lost
bigendlessholeinspace
molecularcloud protostar supergiant typeIIsupernova blackhole
musesupermassiveblackholeequalsawesome
inescapable dense eventhorizon redshift singularity
nospace powerfulgravitationalfield absorbslight gasspiralsinward gravitationalfield
vacuum toilet dark gravitationalpull bottomless
dark mysterious confusing crazy cool
dense nolightescapes gloryhole dark stretch
bent time space stay away
eh
intense engulfing mysterious complicated black
vacuum black mysterious big hole
mass collapsed preventsescape radiation
event horizon space time curvature
gravity wormhole eventhorizon accretiondisc escapevelocity

Student responses
Section 70160

nothing notevenlightescapes
gravity trap spaghettified pinwheel galaxy
dark mysteriouspossibilities undiscovered, nothing
gravity massive lighteater swirling, dark
mass/density >670616629mph escapevelocity eventhorizon condensation
black hole time disappear forever
dark big eats sucks destructive scary
gravity space starsdustcloudscollapse
blackhole idontknow
infinite endless deep dark scary
neverendingtime warpedspace
Ihavenoidea
gravity black spacetime compacted timetravel
gravitationalfield nolight noreturn onewaysurface scary
dark scary invisible blackbody nolight gasspirals
escapevelocity singularity eventhhorizon Schwarzschildradius timedilation
ican'tthinkofany sorry
black hole space infinity everthing
space singularity time gravity nonrotating
infinity deep bottomless vacuum gravity
hole black empty nolight gravitationalpull
dark gravity mass heavy tunnel
singularity eventhorizon Schwarzschildradius escapevelocity gravity
mystery darkness death massivestardeath scary
nonrotating ecectricalcharges light eventhorizon volumeofspace
type2supernova supernova nova hydrogen
blackhole deep long dark

Astronomy quiz question: mass, densities, and event horizons

Astronomy 10 Quiz 10, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q10.1

[3.0 points.] Which one of the following choices best explains why a black hole is the only object that can have an event horizon?
(A) It has zero density.
(B) It has infinite mass.
(C) It has zero size.
(D) It has infinite energy.
(E) It can distort spacetime.

Correct answer: (C)

Section 4160
(A) : 5 students
(B) : 7 students
(C) : 15 students
(D) : 1 students
(E) : 2 students

Section 5166
(A) : 6 students
(B) : 16 students
(C) : 11 students
(D) : 3 students
(E) : 5 students

Previous posts:
Astronomy clicker question: masses, densities, and event horizons.
Astronomy in-class activity: masses, densities, and escape velocities.

Astronomy clicker question: masses, densities, and event horizons

Astronomy 10, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q10.1

Students were asked the following clicker question (Classroom Performance System, einstruction.com) near the end of their learning cycle (specifically, following the astronomy in-class activity: masses, densities, and escape velocities).

[0.3 points.] Why is a black hole the only object that has an event horizon?
(A) Because of its mass.
(B) Because of its density.
(C) Because of both its mass and density.
(D) (Neither its mass nor density matters.)

Correct answer: (B)

Student responses
Section 5166
(A) : 1 student
(B) : 21 students
(C) : 14 students
(D) : 3 students

Astronomy in-class activity: masses, densities, and escape velocities

Astronomy 10 In-class activity 23 v.07.04.25, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q10.1

Students find their assigned groups of three to four students, and work cooperatively on an in-class activity worksheet to determine the relationship between the escape velocity with mass and/or density.

Start off with filling some of the entries for the students, before they start working in their groups. The main sequence star on the left is the smallest and least massive of the main sequence stars: "G2," "1.0 M_Sun." Point out the progression in increasing size and mass of the main sequence stars, from right-to-left. Also point out the progression in decreasing size from left-to-right for the compact objects, and also the increasing escape velocities. Undoubtably the compact object with zero size and an infinite escape velocity is the black hole.
There will be several ties for the list of increasing masses:

G2 = white dwarf; A3 = neutron star; B3 = black hole.

However, there is no trend in escape velocities for this list, such that there is no relationship between the mass and escape velocity.

There are also several (approximate) ties for the list of increasing densities:

G2 = A3 = B3; white dwarf, neutron star; black hole.

Since the escape velocities also increase from left-to-right along this list, there is a direct relationship between the density of an object and its escape velocity.

Follow-up post: Astronomy clicker question: masses, densities, and event horizons.

Astronomy clicker question: entering the event horizon

Get into vortex you say, by ?rico Lopez
icanhascheezburger.com
January 3, 2008

Astronomy 10, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q10.1

Students were asked the following clicker question (Classroom Performance System, einstruction.com) at the start of their learning cycle:

[0.3 points.] Why is entering the event horizon (the "Schwarzchild radius") surrounding a black hole considered a "point of no return?"
(A) All matter is crushed into nothingness.
(B) All matter is instantly converted into energy.
(C) The escape velocity is faster than the speed of light.
(D) Time runs backwards.

Correct answer: (C)

If students ask about what's inside the event horizon of a black hole, point out that they could certainly try to enter it and find out for themselves. However, in the very unlikely event that would be able to survive the journey, they would not be able to tell anyone in the outside universe about their discoveries, as nothing, not even light would be able to escape from within the event horizon. So they should bring a friend to share in the experience. Otherwise, it'd be lonely in there...

And yes, the expression on the middle kitten is priceless.

Student responses
Section 4160
(A) : 9 students
(B) : 4 students
(C) : 17 students
(D) : 0 students

Section 5166
(A) : 7 students
(B) : 7 students
(C) : 23 students
(D) : 0 students