GRB 130427A, an interesting burst of gamma radiation during finals week

An interesting gamma ray burst happened during finals week, GRB 130427A

Back in the early 1960s, the United States launched a few satellites, the Vela satellites, to detect secret nuclear weapons testing by the Soviet Union. By treaty between the US and USSR, no one was to test nuclear weapons above ground; underground testing was permitted. To monitor the Russians, US scientists at Los Alamos developed the Vela platform.

Nobody ever saw the Russkies nuking off any above ground tests, but while the detectors were not over Siberia, they could definitely see bursts of high energy gamma rays from sources outside the solar system.

Excellent.

In the 1970s, they began publishing scientific studies of these gamma ray bursters. The image below is an animation of the April 27 burst. Click the image to see the animation.

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There is still a lot of study going on as to why these GRBs happen all over the universe. We do not know for sure, and neither do the Russians. This GRB was so close and so well-imaged, that maybe someone will now crack the puzzle, using F = ma and all the concepts we study in PHY2048 and PHY2049.

Grades going UP

I just hoisted the WebAssign homework pointage, your labs pointage and updated class participation. Also, the best 8 written homework scores are up.

I am still working on the final exam problems, and I expect to finish them tonight. Look for them to be uploaded tomorrow morning.

And everything has to be done and semester grades uploaded to the registrar by noon Friday. Still a ton of stuff to do.

Scantron scores are IN.

You can see that the scantron scores are in as of about 8 AM today. I will unmute them, then convert to the pointage: double the raw score, because it is two points per item.

I have not even attacked any of the problems yet, being as how I have been as busy as a subhumanoid maniac with my other finals, the last of which is today. I expect to start grading tonight or so.

Let's see how it goes.

As predicted

As Clubber Lang once predicted for his boxing opponent, so I have experienced whilst uploading your graded homework files: Pain.

It was so painfully slow, it made me want to grade more papers -- i.e., I was delirious.

Anyway, your HW 10 papers are all out to you, and your score is UP. I shall see you in 24 hours, 1:00 PM, in our lecture hall, for the final exam. Bring scantron, calculator, pencils, and be ready.

Pressure under the sea solution UP

You can now view the solution PDF for homework 10.

Homework 10, pressure under the sea

I have your written homework assignment set up in PDF, on Webcourses2.

I think you will want a good table of integrals to execute this assignment properly.

Combo homework in WebAssign

Your WebAssign homework for Monday is now available. It is a combination of Ch. 13 problems on universal gravitation and Ch. 14 problems concerning fluids. It is due on Monday, April 15, 3:30 PM.

From Earth to the moon

Homework 9 is ready in PDF, on Webcourses2.

Monday lecture in PDF only

Sorry! The audio data yesterday pooped out somehow. So your lecture podcast is canned, but you can download the PDF document of the slides in iTunes U:PDFs.

Written hw 8 is ready

You can now view the written homework due on Friday, concerning moment of inertia.

revision

I revised the assignment slightly, so that you can use both sides of the paper, this assignment only. The new PDF has replaced the one from last night.

By the way, both PDFs include the answer for the scattering angles in the problem we started in lecture. SO.... if you can finish that problem we started, getting the right scattering angles, you can then apply the same method to the actual homework to hand in.

Scattering

Your written homework #7 is a scattering problem similar to the one we tackled in lecture today. The PDF is now available in WebCourses2.

Deluxe scattering machine in Geneva, Switzerland.

Last week's podcasts

I have embedded the doc cam work from Wednesday and Friday into the lecture podcasts, which are uploading now. Lots to learn.

This and that

I am working on some odds and ends in Webcourses2, including updating the iClicker 2 data. Friday's lecture data is now up, and that makes the semester's question count 44, as of Friday's lecture.

I also created a new line on your Grades page, showing the estimate of your class participation points on the semester grade, out of 48 possible, as if I were to compute semester grades today. If you have more than 37 answers (i.e., more than 85%), then your pointage is 48/48. Otherwise it is scaled following the method on our syllabus.

Note: This is a preliminary estimate. Your iClicker 2 participation pointage can definitely change, because there are a lot more iClicker 2 questions between now and the end of April.

Get going on Monday's WebAssign homework.

There is a smorgasbord of two-dimensional collision problems in your WebAssign homework for Monday. Your are GO for launch.

Homework 6 is ready.

Your written homework #6 in PDF is now ready for download. GO! GO! GO!

Normal operations resume at noon.

Just got the all clear from UCF:

UCF Main campus will resume normal operations at noon. Tower 1 remains evacuated.

I will see you at lecture, 3:30 PM.

Main campus closed until noon, Monday.

Emergency alert:

University of Central Florida’s main campus is closed for classes and employees until noon. Essential personnel should report to work.

Any class scheduled to begin before noon today, is cancelled.

I hope we will be cleared for our lecture meeting at 3:30 PM. Be prepared to attend.

updates

Next WebAssign homework is ready.

Your WebAssign homework is ready to activate at 10:00 AM this morning.

Study in chapter 9 as far as the center of mass concept, p. 254.

The first two exercises are about center of mass. Problem 6 is one we worked on in lecture, Friday afternoon. The last exercise in this assignment is one of the brain burners that you have to work on sequentially and finish -- or get no points.

Remember to use your eyes and diagram carefully.

We will take Friday off today.

We are quite a bit ahead of where my class was last semester at midterm. Good.

That being the case, we can take this Friday off from lecture, and I will see you on Monday, after spring break.

Keep your eye on Webcourses2, however, because I will be grading the exam and posting scores in the next few days.

So keep your pocket protectors squared away, and enjoy your spring break!

Scantron scores are UP.

Your scantron scores are UP in Webcourses2.

Each item was 2 points, so your score reflects the number you got correct ×2.

Yesterday's podcast is UP, but...

Yesterday's lecture podcast is UP, on our iTunes U area, but the audio seems to cut out midway. All the slides are there, though, as usual, in the artwork track, including the scans of the document cam pages.

So everything you saw is there, but not quite everything you heard.

Written homework 5 is ready.

Go download your PDF of written homework #5. It includes some "push" goals if you really want to prepare diligently for the midterm examination.

Office hours tomorrow are 11 AM - noon, PS158 in the Physical Sciences Building.

Written homework 4 is graded and ready.

In Webcourses2, I have posted everyone's grade for written homework #4. I will hand them back in lecture today.

WebAssign homework is ready.

Your WebAssign homework for Monday is ready.

In addition, the diagram above and the following queries* are something to consider as you study:

1. Two blocks, of masses M = 3 kg and m = 2 kg, are in contact on a horizontal table.
2. A constant horizontal force of magnitude F = 5 N is applied to block M as shown.
3. There is a constant frictional force of magnitude f = 1 N between the table and the block m, but
4. no frictional force between the table and the first block M.

That being the case, can you calculate the acceleration of the two blocks? Can you calculate the force of contact between the blocks?

Inquiring minds want to know!

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* Adapted from French, A.P., Newtonian Mechanics, New York: W.W. Norton, 1971.

Class cancelled today, Wednesday

Due to evacuation of the MAP building, we will cancel lecture today, Wednesday.

I will see you on Friday, so bring that written homework and I will collect it on Friday.

Written homework 4 is ready.

Your written homework assignment for Wednesday is now UP in Webcourses2.

Updating iClicker 2 data

I have been updating iClicker 2 data this afternoon. Still some data sets to upload, but it is getting caught up.

If your clicker is #8514BC2D or #8DA2A28D...

If your clicker is #8514BC2D or #8DA2A28D, you are not earning any points for your semester grade. I can see you are clicking but I have no idea who you are. It is long past the time when your iClicker 2 registration was to be squared away.

Written Homework 4 will be ready Monday, due Wednesday.

Looking ahead, you'll get a new written homework assignment on Monday, probably related to work and energy.

That puts us back in the standard homework cycle. It will be due on Wednesday, returned on Friday.

WebAssign homework is ready now.

To see where we are heading in the next few weeks, this page, Kinetic energy etc., at Wolfram's ScienceWorld can give you a good idea.

Your WebAssign homework due on February 18 is now ready. This is a big assignment because energy is a big topic and very useful, so mastery is a good goal.

Image: Deep Impact probe collides with comet Tempel 1. [NASA]

Written homework 3 is UP.

You can now drop down the PDF of written homework #3 from Webcourses2. It is due on Friday at the beginning of lecture.

Iceland

I have posted your grades for the Iceland homework. Tomorrow I will hand it back. Until then you can view my solution in PDF on the "Written homework assignments" page.

Variations in the gravity of our moon

An interesting look at variations in the gravitational field of our moon, from the GRAIL spacecraft. Cf., Zuber et al., Science 8 February 2013: Vol. 339 no. 6120 pp. 668-671. DOI: 10.1126/science.1231507

Mercator projections of free-air gravity, topography, and Bouguer gravity. Frames in (A) highlight the area surrounding the Korolev impact basin, at center. Frames in (B) show the western limb of Oceanus Procellarum. Details of free-air and Bouguer gravity are the same as in Fig. 1. Topography is from a LOLA 1/64° grid.

1000 mGal = 1000 milliGalileos = 1 cm/sec². So the variations are small but telling.

Enjoy.

New WebAssign is ready.

Your WebAssign homework is ready now. It includes on problem from Ch. 5, so do a bit of reading ahead into Ch. 5 for Monday.

iTunes U up to date

For those of you using the visual podcast in our iTunes U area: it is updated now with the last few lectures. Notes, diagrams, equations etc. are in the artwork track. Click the square icon in the left side of the progress bar, and it will pop out the artwork full screen, in HD.

Hint

Hint for written homework 2.

1. Part 2 is maybe tougher to think through, but the math is not that hard.
2. Part 1 will require some quadratic formula to solve, but part 2 does not.
3. Equations for x(t) and y(t) of the artillery round are not the only equations you'll need.
4. You can make a nice diagram on a piece of standard graph paper (in landscape mode), using 1 block for each kilometer.
5. Make use of the four significant figures in your calculations!

Sweet high speed photo of USN 5-inch naval rifle taking a test shot.

Homework 2 is UP.

Your second written homework PDF is now UP in Webcourses2.

Interesting side question

It would be an interesting side question to ask, in the artillery problem, whether the artillery shell is still on the way up when it hits or has it gone over the top of its arc and started heading down when it hits.

By the way, they use artillery out west for this purpose. I have seen them do it in the Bridger Range, near Bozeman, Montana.

Homework ready

The assignment for Monday, January 28, is now ready in WebAssign.

Be especially careful with your work on the last two items, problems 12 and 16. We will discuss one or both of those two problems on Monday.

Motion capture

We are studying basic quantities that describe motion: position, velocity, acceleration. It is interesting to think about the motion capture software by which television and film producers create exotic beings.

Input: position, velocity, acceleration deluxe.

Output: scary monsters from outer space.

Excellent.

Homework in WebAssign is set for 1/23/

You have a new assignment in WebAssign, due next Wednesday, 3:30 PM. GO! GO! GO!

Other than that, have a great long weekend.

Homework 1 grades are up.

The moped problem for writtern homework assignment #1 is now UP in Webcourses2.

The substitute lecturer, Dr. James Cooney, will pass your papers back to you tomorrow (Friday) in lecture.

Office hours, 11 AM

I will be available for office hours consultation at 11 AM today, until noon. Come to room PS158 in the Physical Sciences Building.

Homework 1 is ready

There is now a PDF of homework assignment 1 on its own page in Webcourses2. Look for the red apple image.

Work carefully and well. This assignment is due on Wednesday at the beginning of lecture.

Sentences

See if your decoded sentences show up legibly in the Webcourses2 grades page. I have all the statements decoded, and I have uploaded them back to the gradebook, but I am not sure your code and sentences are actually visible.

Historical record

Monday you will get your first written homework assignment, due on Wednesday. The written homework forms a large chunk of your semester grade. Check the diagram above; the volume of each sphere is proportional to the weight of each part of your semester grade.

That being the case, I have set up a set of files to show you what to expect. You can now view all the homework assignments, with solutions, from last semester. Look for the "Historical record" blurb page in Webcourses2.

Jan. 9 podcast now up

Your podcast of Tuesday's lecture is now available.

HW in WebAssign going OK.

The homework for tomorrow looks like it is going okay for the students who have signed up.

For those of you who have not gotten enrolled in WebAssign, you had better get on it. Do not be caught napping!

Fluid dynamics, ahead: the Orion Bullets.

Interesting view, many light years away in the Orion Nebula, of fluid turbulence in clusters of stars.

When we get to fluid dynamics later in the semester, we will tackle some basic problems that form a foundation for, eventually, understanding the Orion Bullets. Excellent.

iTunes U

Our lecture podcast is now available in iTunes U. There is a blurb page in Webcourses2 on how to subscribe.

Office hours

Office hours will be in room PS158, Physical Sciences Building, on Tuesday mornings, 11 AM - noon.

Here is a YouTube about how to find the Physical Sciences Building.

Excellent place to work

Cool place to work, the National Ignition Facility, building an inertial confinement laser fusion system. Nice.

Computer science majors: Check slide #9 for the leopard imaged by those lasers. Amazing.

Those of you who are aspiring physicists and engineers and computer scientists, this is the kind of job you should consider a target. When I challenge you to excellent performance, it is because I am thinking of you taking this kind of job. Good.