In Chapter 3, subsection “A Closer Look at Physics Bodies”, sidebar box “The Gravity of the Situation”:
It refers to “speed” when it should be “acceleration”. 9.8m/s is the rate of acceleration for a falling object on Earth (in the absence of resistance).
Thanks (I’m just a few chapters in, but finding the book good and useful so far).
This might be my favorite thread.
The short story is this: you are correct, so I’ve updated the book. Thank you. 
The longer story, and the reason why I really like this thread, is because I didn’t realize the difference between speed and acceleration—at least not in the context of Earth’s gravity. I guess I never really gave it much thought, to be honest, but your comment sparked a desire for me to learn more about it.
So, I found a few articles, watched a few videos, and learned something new—and probably something I should have already known, so thank you (again).
P.S. I’m glad you’re enjoying the book.
I have such a big happy grin reading your response 
Physics was the one field of science I really geeked out on in school. The stuff around velocity (measuring instantaneous velocity vs. the positional graph of an object over time, etc.) totally fascinated me and has stuck all these years later (when so many others of my early school lessons are lost to the embers of time 
).
As to the book, I’m a couple more chapters in and still enjoying it. Hoping to get a youngling in my life interested in collaborating on making a little game (or more than one) to get her engaged in coding.
