P-dog's blog

Accretion disk radiation

2008-07-20T00:05:00.000-07:00

"Brewster Rockit: Space Guy!" by Tim Rickard
July 5, 2008

There would probably be x-rays rather than near-UV rays emitted from the accretion disk surrounding a black hole, or perhaps beta particles (whether electrons or positrons) from Hawking radiation, especially if the black hole was sufficiently small.

Pluto marquee

2008-07-19T00:05:00.000-07:00

Flickr.com: (Untitled), by CommandZed
November 19, 2006

Don't we all?

"Space is the Place" t-shirt

2008-07-18T00:05:00.000-07:00

Space is the Place"
The Imaginary Foundation

Because in space, no one can hear you jam.

"Teach the Controversy" t-shirts

2008-07-17T00:05:00.000-07:00

"Classical Periodic Table, by Jeremy Kalgreen
controversy.wearscience.com

"Geocentric Universe" by Jeremy Kalgreen
controversy.wearscience.com

"Intelligently designed t-shirts urging you to show both sides of every story..."

Mars Phoenix Mission

2008-07-16T11:38:00.000-07:00

"Mars...robot arm grabs handful of soil"
The Sun
June 2, 2008

How did the scoop mark wind up looking like a footprint?

"It puts the mars soil sample in the scoop" by Unknown
punditkitchen.com
July 2, 2008

The Sun--Brightening Your Days For 5x10^9 Years

2008-07-15T11:34:00.000-07:00

Photoshop Phriday: Unnecessary Advertisements, by the_ruiner
somethingawful.com
June 20, 2008

Also, do not taunt the Sun...

Astronomy snow-globe

2008-07-14T11:26:00.000-07:00

"Traveler 87 At Night (Between Too Much And Me)"
("Traveler" series, 2001-2007)
by Walter Martin and Paloma Muñoz, 2004
martin-munoz.com

Perhaps one of the less ironic artistic snow-globes by these two artists.

Hawking vs. Einstein, part four

2008-07-13T11:14:00.000-07:00

Stephen Hawking at the Lido, Avenue Champs-Elysees, Paris, France
The Pop Culture Travel Guide (jaunted.com)

Stephen Hawking...triumphant!

Hawking vs. Einstein, part three

2008-07-12T11:10:00.000-07:00

hawkspace.jpg, by OchreJelly
brickshelf.com

Stephen Hawking, triumphant? Open the pod bay doors, AL!

Hawking vs. Einstein, part two

2008-07-11T00:01:00.000-07:00

"A Long-Awaited Taste of Outer Space," by Steve Boxall
WashingtonPost.com, April 27, 2007

"Einstein in Schpace," by robotlick
Worth1000.com
Ultimate Comebacks contest.

"So, how do you like them apples, eh?"

Hawking vs. Einstein, part one

2008-07-10T00:01:00.000-07:00

Sluggy Freelance, by Pete Abrams
(Guest artwork by Michael Scandizzo)
sluggy.com
January 11, 2003

The downside of astrology

2008-07-09T00:01:00.000-07:00

"The Stars Are Against Me Tonight" by Dan-ah Kim (dkim-art.com)
Mixed Media, 15" by 19"
"Departing Flights" exhibit at Thinkspace Art Gallery
Los Angeles, CA, June 13 to July 4, 2008

The fault, dear reader, is not within us, but in the stars themselves...

Over easy, or scrambled?

2008-07-08T00:01:00.000-07:00

"But They Only Warn You About One" by Jessica Hagy
indexed.blogspot.com, June 10, 2008

Of course, everyone knows that in order to make scrambled eggs, you must first beat them.

Physics quiz question: Mountain Dew AMP(TM) caffeine consumption rate

2008-07-07T00:05:00.000-07:00

Physics 8A Quiz 1, Fall Semester 2005
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.1

(Cf. Young and Freeman, University Physics, 11/e, Exercise 1.6.)

[3.0 points.] Suppose that you drank a Mountain Dew AMP(TM) beverage (containing 113 mg of caffeine) twice a day. Which one of the following choices best describes your average intake of caffeine in grams per second, if you do not drink any other caffeinated beverage?
(A) 2.62 x 10^-6 g/s.
(B) 5.12 x 10^-5 g/s.
(C) 1.95 x 10^-4 g/s.
(D) 0.382 g/s.

Correct answer: (A)

The intake in grams per second can be determined from converting the units from the given rate of 226 mg per day:

(226 g/1 day) * (1 g/1,000 mg) * (1 day/24 h) * (1 h/3600 s).

Response (B) is the result of 1,000/(226*3600*24); response (C) is 226*3,600*24/1000, but with the resulting 10^4 exponent switched to 10^-4; while response (D) is 3,600*24/(226*1,000).

Student responses:
(A) : 31 students
(B) : 3 students
(C) : 5 students
(D) : 0 students

Physics quiz question: gas consumption rate

2008-07-06T00:01:00.000-07:00

Physics 8A Quiz 1, Fall Semester 2005
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.1

(Cf. Young and Freeman, University Physics, 11/e, Exercise 1.9.)

[3.0 points.] The gasoline consumption of a small sedan is advertised as 30.0 miles per gallon. Which one of the following choices best corresponds to this value in meters per milliliter?
(A) 4.93 x 10^-5 m/mL.
(B) 12.8 m/mL.
(C) 70.6 m/mL.
(D) 78.4 m/mL.

Correct answer: (B)

The gasoline consumption can be expressed in meters per milliliter using unit conversions:

(30 mi/gal) * (1.609 km/1 m) * (1,000 m/1 km) * (1 gal/3.785 L) * (1 L/1,000 mL) = 12.8 m/mL.

Response (A) is (30/(1,609*3.785)); response (C) is (30*3,785)/1,609; response (D) is 3,785/(30*1,609).

Student responses:
(A) : 28 students
(B) : 0 students
(C) : 0 students
(D) : 0 students

Physics quiz question: unit conversion discrepancies

2008-07-05T00:24:00.000-07:00

Physics 8A Quiz 1, Spring Semester 2005
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.2

(Cf. Young and Freeman, University Physics, 11/e, Exercise 1.15.)

[3.0 points.] Compare the exact relation of 1 inch = 2.54 cm with the approximate relation 39.37 inches = 100 cm. Which one of the following choices best corresponds to the percent discrepancy between using these relations to determine how many inches there are in one meter?
(A) 0 %.
(B) 0.0002%.
(C) 0.0079%.
(D) 0.01%.

Correct answer: (A)

The "observed" value of inches in one meter would be 39.37 inches, while the "expected" value would be based on the 1 inch = 2.54 cm relation:

1 m * (100 cm/1 m) * (1 inch/2.54 cm) = 39.370078740157... inches.

Then the difference between the observed and expected value would be:

39.37 inches - 39.370078740157... inches = 0.000078740157... inches,

or two decimal places, 0.0 inches. This makes the percent discrepancy 0%, to the correct number of significant figures.

Response (B) uses too many significant figures; response (C) does not divide by the expected value in converting the discrepancy into percent discrepancy; response (D) is as (C), but rounded up.

Student responses:
(A) : 15 students
(B) : 34 students
(C) : 10 students
(D) : 10 students

Physics quiz question: drinking Red Bull(TM)

2008-07-04T00:01:00.000-07:00

Physics 8A Quiz 1, Fall Semester 2004
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.1

(Cf. Young and Freeman, University Physics, 11/e, Exercise 1.7.)

[3.0 points.] Suppose that you drank a Red Bull(TM) beverage (containing 80.0 mg of caffeine) once every other day. Which one of the following choices best describes your average intake of caffeine in grams per second, if you do not drink any other caffeinated beverage?
(A) 4.63 x 10^-7 g/s.
(B) 5.79 x 10^-6 g/s.
(C) 2.22 x 10^-5 g/s.
(D) 2.78 x 10^-4 g/s.

Correct answer: (A)

The intake in grams per second can be determined from converting the units from the given rate of 80.0 mg per two days:

(80.0 mg/2 days) * (1 g/1,000 mg) * (1 day/24 h) * (1 h/3600 s).

Response (B) is the result of ingesting 1 mg of caffeine every other day; response (C) is from drinking one Red Bull(TM) beverage every hour; response (D) is the result of ingesting 1 g of caffeine every hour.

Student responses:
(A) : 40 students
(B) : 3 students
(C) : 3 students
(D) : 0 students

Physics quiz question: monolith surface area

2008-07-03T00:01:00.000-07:00

Physics 8A Quiz 1, Spring Semester 2004
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.2

(Cf. Young and Freeman, University Physics, 11/e, Exercise 1.14.)

[Version 1]

[3.0 points.] A solid model of a monolith has rectangular dimensions of 1.00 units x 4.00 units x 9.0 units. Which one of the following choices best describes the total surface area (in units^2) of this monolith?
(A) 9.8 x 10^1 units^2.
(B) 9.80 x 10^1 units^2.
(C) 1.0 x 10^1 units^2.
(D) 1.00 x 10^1 units^2.

Correct answer: (A)

Student responses:
(A) : 28 students
(B) : 8 students
(C) : 4 students
(D) : 0 students

[Version 2]

[3.0 points.] A solid model of a monolith has rectangular dimensions of 1.000 units x 4.000 units x 9.00 units. Which one of the following choices best describes the total surface area (in units^2) of this monolith?
(A) 9.8 x 10^1 units^2.
(B) 9.80 x 10^1 units^2.
(C) 1.0 x 10^2 units^2.
(D) 1.00 x 10^2 units^2.

Correct answer: (B)

Student responses:
(A) : 6 students
(B) : 27 students
(C) : 2 students
(D) : 1 student

The dimensions of the monolith from Arthur C. Clarke's 2001: A Space Odyssey are, of course, known to much more significant figures than given here.

Physics quiz question: elapsed round-trip distances

2008-07-02T00:01:00.000-07:00

Physics 8A Quiz 1, Spring Semester 2004
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.1

(Cf. Young and Freeman, University Physics, 11/e, Exercise 1.1.)

[Version 1]

[3.0 points.] Suppose that the round-trip mileage between your home and Cuesta College is 48.0 miles. If you were to travel to and from campus five days a week, and there are 18 whole weeks of class in a semester, which one of the following choices best describes the number of semesters that you would need to drive a total of 6,000 miles between your home and campus?
(A) 0.576 semesters.
(B) 0.720 semesters.
(C) 1.39 semesters.
(D) 1.74 semesters.

Correct answer: (C)

This can be solved by ensuring that units cancel to result in 6,000 miles:

6,000 mi = (48.0 mi/1 trip) * (5 trips/1 week) * (18 weeks/1 semester) * N,

where N is the number of semesters.

Response (B) is the inverse of the correct response (C).

Student responses:
(A) : 0 students
(B) : 4 students
(C) : 31 students
(D) : 0 students

[Version 2]

[3.0 points.] Suppose that the round-trip mileage between your home and Cuesta College is 48.0 miles. If you were to travel to and from campus only four days a week, and there are 18 whole weeks of class in a semester, which one of the following choices best describes the number of semesters that you would need to drive a total of 6,000 miles between your home and campus?
(A) 0.576 semesters.
(B) 0.720 semesters.
(C) 1.39 semesters.
(D) 1.74 semesters.

Correct answer: (D)

This can be solved by ensuring that units cancel to result in 6,000 miles:

6,000 mi = (48.0 mi/1 trip) * (4 trips/1 week) * (18 weeks/1 semester) * N,

where N is the number of semesters.

Response (A) is the inverse of the correct response (D).

Student responses:
(A) : 2 students
(B) : 1 student
(C) : 1 student
(D) : 32 students

Physics quiz question: speed conversion

2008-07-01T00:01:00.000-07:00

Physics 8A Quiz 1, Fall Semester 2003
Cuesta College, San Luis Obispo, CA

Physics 8A learning goal Q1.1

(Cf. Young and Freeman, University Physics, 10/e, Exercise 1-7.)

[3.0 points.] Consider the pop rock group t.A.T.u's album title "200 km/h In The Wrong Lane." Which one of the following choices best describes this speed in feet per second?
(A) 124 ft/s.
(B) 136 ft/s.
(C) 182 ft/s.
(D) 322 ft/s.

Correct answer: (C)

To convert km/h into ft/s:

(200 km/h) * (1,000 m/1 km) * (3.28 ft/1 m) * (1 h/3,600 s) = 182 ft/s.

Response (A) is 200/1.609; response (B) is 200*(3,600/5,280); while response (D) is 200*1.609.

Student responses:
(A) : 1 student
(B) : 1 student
(C) : 35 students
(D) : 1 student

Weight vs. mass, and significant figures

2008-06-30T00:01:00.000-07:00

Shoe, by Chris Cassatt, Gary Brookins, and Susie MacNelly
December 10, 2007
macnelly.com

Nevermind the confounding between weight and mass--how did Professor Cosmo Fishhawk gain an extra significant figure?

Two-way vector

2008-06-29T00:01:00.000-07:00

Photoshop Phriday: Signs Of Our Times II, by occamsmonkey
somethingawful.com
August 3, 2007

Maybe it's a tensor.

Kudos: from Physics 5A students, Spring Semester 2008

2008-06-28T00:01:00.000-07:00

"Sorry I wasn't a more responsible student" by Student 2012
Physics 5A
May 2008
Cuesta College, San Luis Obispo, CA

"I understand the amount of work necessary" by Student 2880
Physics 5A
May 2008
Cuesta College, San Luis Obispo, CA

Kudos: from Astronomy 10 students, Spring Semester 2008

2008-06-27T00:01:00.000-07:00

"...But was interested always" by Student 5352
Astronomy 10
May 2008
Cuesta College, San Luis Obispo, CA

"See you next semester" by Student 3512
Astronomy 10
May 2008
Cuesta College, San Luis Obispo, CA

The end of time

2008-06-26T00:01:00.000-07:00

Sinfest, by Tatsuya Ishida
www.sinfest.net
September 17, 2007 (excerpt)