# Discuss part 1 of David Tong's Classical Dynamics class notes

• June 23, 2012 · 11:00 AM

We will be discussing the first of four parts of David Tong's course notes on Classical Dynamics.  The notes (only about 9 pages long) can be found here:    http://www.damtp.cam.ac.uk/user/tong/dynamics/one.pdf.

(Alternatively, if you go to David Tong's "Lectures on Classical Dynamics," you will find the same notes under "1. Newtonian Mechanics," by clicking on the "PDF" link.)

Please review these notes before the meeting, and write down any steps you do not understand perfectly, or for which you could use more intuition.  Post your questions to our meetup page in advance, if possible, so that others can think about how to explain it to you at the meeting.

We should have Wi-Fi and a dry-erase or some equivalent thing on hand.  I'll post more when I know more, e.g., whether they allow food there.  The library is here:

Seward Park Library, 192 East Broadway (at Jefferson St.), New York, NY[masked]

It's on the Lower East Side, near the E. Broadway stop on the F, the Grand Street stop on the B/D, and the Essex Street stop on the J/M/Z trains.

• ##### Matt S.

Maybe we could also talk about the 10 Galilean transformations, under which inertial reference frames remain inertial. The question is: When you formally demonstrate this result, how do you use the orthogonality of the rotation matrices?

June 11, 2012

• ##### Matt S.

Greg, Thanks for your thoughts. (Welcome to the group, by the way. I'll dispense with the usual "welcome" email because you are already diving in.) I agree with your answer, but it addresses the part about a zero-curl field being expressible as a gradient of a scalar field. I am interested in the other piece: Why a zero-divergence field must be expressible as the curl of a vector field -- a "vector potential." I have some clues, but would love some help on details at the mtg.

June 11, 2012

• ##### Matt S.

Tong says, at Eq. 1.8, that any zero-curl field must be expressible as the gradient of a scalar field. I think I see why that's true geometrically. But, I believe it's also true (and undoubtedly related) that if the divergence of a field is everywhere zero, then that field must be expressible as the curl of some other field. (This is why, e.g., we can write the magnetic field as the curl of the vector potential.) I could use help with the geometry of this second piece.

1 · June 6, 2012

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