RFG 2018 Conference


Shaking it up with AZGS’ Earthquake Fault Videos

As part of our earthquake preparedness program, ‘Arizona has Earthquakes’, we've produced a suite of video shorts showcasing active fault systems in Arizona. Our objective: to inform the Arizona public and decision-makers of the nature, magnitude and frequency of earthquakes impacting Arizona.

For video titles, viewership and links see the post at our new blog site: http://blog.azgs.arizona.edu/ 

March 21 meeting of the Paleontological Society of Washington

The Paleontological Society of Washington

7:00 pm, Wednesday, March 21

National Museum of Natural History, Constitution Ave. entrance

The biology of Trichoplax adhaerens and how it relates to the evolution of Metazoa

Carolyn Smith

National Institute of Neurological Disorders and Stroke,

National Institutes of Health, Bethesda, MD

April 2018 Issue of the ‘African Geographical Review’ Now Available

The AAG is pleased to announce that Volume 37, Issue 1 (April 2018) of the African Geographical Review is now available. The full table of contents for this issue is below and can also be accessed here. The African Geographical Review is the journal of the Africa Specialty Group of the American Association of Geographers. It provides a medium for the […]

Jounce, Crackle and Pop

I saw this T-shirt recently, and didn't get it. (The joke or the T-shirt.)

It turns out that the third derivative of displacement \(x\) with respect to time \(t\) — that is, the derivative of acceleration \(\mathbf{a}\) — is called 'jerk' (or sometimes, boringly, jolt, surge, or lurch) and is measured in units of m/s³. 

So far, so hilarious, but is it useful? It turns out that it is. Since the force \(\mathbf{F}\) on a mass \(m\) is given by \(\mathbf{F} = m\mathbf{a}\), you can think of jerk as being equivalent to a change in force. The lurch you feel at the onset of a car's acceleration — that's jerk. The designers of transport systems and rollercoasters manage it daily.

$$ \mathrm{jerk,}\ \mathbf{j} = \frac{\mathrm{d}^3 x}{\mathrm{d}t^3}$$


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