Thanks. I calmed down a bit and sent him an email about how it would help me to have worked problems and how maybe he shouldn't worry about students who decide not to do their work if he makes answers available for them...

It can be hard as a teacher to know what is going on for students... Especially when they don't communicate with you... I think it is probably most likely to be that. He simply flies through the maths... I think because the maths is easy for him. So he's spending more time on the conceptual stuff because physics people often seem to have this idea that people get through physics from being good at maths without 'really understanding' any of it.

I'm different because I can justify / rationalise pretty much anything. But a 'simple unit conversion' is likely to totally screw me over. Sigh.