Does it touch on mixing / mastering at all? I have a suspicion that some of my friends will be looking to me to put together some demos in the near future, so I'd be very interested in some beginner/intermediate knowledge around that.

I read an enormous amount on mixing/mastering and was still rubbish. It's hard to write about perception of sound.

I would recommend instead finding a well reputed mixing/mastering engineer who offers lessons and pay for some. Bring them your best mix (in the DAW on your laptop) ask them where it is wrong and how to improve it. Shouldn't take more than a couple of hours. In my case this cost around £100 (http://oood.net/mastering/about-stooodio-mastering) and helped enormously. My friends now think I'm great at "mastering" by which they mean mixing, I have nothing even approaching mastering engineer ears & I suspect Colin still wouldn't think much of my mixes either but that's why I'll happily pay him to master them if I ever have time for music again :)

I know there are online practical courses these days, in theory these could be better than a book as they would have audio/interactive examples. No idea if they actually are any good though.

Basically forget learning to master though. For your friend's demo, learn to do a reasonable mix then slap a limiter on the main output and boost the loudness as much as you can without losing quality.

Check out the Mixing Engineer's Handbook by Bobby Owsinski. This has been my de-facto go to for everything from acoustics, studio construction, mixing, mastering and more. Great read, and a wonderful reference to have at your desk.

Mixing Secrets for the Small Studio by Mike Senior is what you are looking for.

Alex Tumay has several great video lectures on Youtube on mixing/mastering.

Does this book tell me how to compute e.g. when a physical object hits another physical object, what the resulting sound will be like?

Or if object X (e.g. speaker cone) moves through air with velocity v(t), what will the sound be like at position P?

I've never read OP's book, but Andy Farnell's Designing Sound has a pretty comprehensive look into physics and sound if that's what you're looking for.

Sounds like you're interested in computational aeroacouatics.

"How to have a number one the easy way" by the KLF is the best book imo. Tells you how, and then why you probably shouldn't bother

That was such a fun read!