The "Old Mo"

A response to DKM's invitation to follow the book meme with the following rules:
1. Pick up the nearest book (of at least 123 pages).
2. Open the book to page 123.
3. Find the fifth sentence.
4. Post the next three sentences.


If you had posted this yesterday, I'd be posting something out of The Golden Compass. (Thanks, J!) Today, however, the nearest book at the moment happens to be the text used in one of the courses I teach, The Physics of Everyday Phenomena, 5ed by W. Thomas Griffith. Therefore, you all get some physics today (w00t!):

"If the defensive back is moving before the collision, his velocity changes abruptly. There must be strong forces at work to produce these accelerations, but these forces act for only an instant. How do we use Newton's laws to analyze this event?"

Page 123 of this book is the first page of a chapter on momentum and impulse. On this page, I learned that the "old mo" refers to momentum, as used by sports announcers when describing the momentum of a game (i.e., to the flow of a game)...although I have never in my life heard of it referred to that way. I'm thinking of renaming our Conservation of Momentum lab to something that cleverly uses the phrase "old mo"...something like, "Every old mo is new again," but, you know, more clever than that.