Graham,

I found your post to be a fun puzzle, and appreciate the useful educational motivation behind it, not least the distinction between how what we do in engineering differs from 'mere' science. (I shall now duck to avoid brickbats from any passing scientists.)

I agree with what you and Alasdair say about cold tap water temperatures. My lazy assumption of something like 15°C-17°C in my laundry arithmetic was inspired by the common assumption of 290K for ambient thermal temperature when doing noise calculations in radio work.


Aladair and Mapj,

I have to admit that I still use a 135 film camera and don't have a digital one yet, apart from an old smartphone - much to the perplexed hilarity of most people, but I've never tried developing film.

Graham,

I found your post to be a fun puzzle, and appreciate the useful educational motivation behind it, not least the distinction between how what we do in engineering differs from 'mere' science. (I shall now duck to avoid brickbats from any passing scientists.)

I agree with what you and Alasdair say about cold tap water temperatures. My lazy assumption of something like 15°C-17°C in my laundry arithmetic was inspired by the common assumption of 290K for ambient thermal temperature when doing noise calculations in radio work.


Aladair and Mapj,

I have to admit that I still use a 135 film camera and don't have a digital one yet, apart from an old smartphone - much to the perplexed hilarity of most people, but I've never tried developing film.