Is it a failing in me...
Oct. 5th, 2014 11:30 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
ffutures...that my big issue with last night's Dr. Who episode wasn't about the metaphors of the story, the dynamics of the characters, or even the big science plot-holes that abounded.
No, my big issue was that you can't use a hand-pumped aerosol in a vacuum. It works by taking air in from the outside and using it to push out the liquid. No air outside equals no pressure to push out the liquid, so no spray.
It might be argued that air trapped in the container would be at a higher pressure than vacuum, so push the liquid out anyway, but if it's that airtight it's probably going to swell up and pop like a balloon anyway.
It's ludicrously tiny compared to the rest of the dodgy science, but somehow it really bugged me. So my overall memory of that story will probably remain as "the one with the dodgy aerosol" which I'm sure is not what was intended.
later - numerous readers have pointed out that I've got it wrong and they did say that it didn't work in a vacuum - my attention must have wandered for a sec. Many apologies. I shall now brood about all the other dodgy science instead.
No, my big issue was that you can't use a hand-pumped aerosol in a vacuum. It works by taking air in from the outside and using it to push out the liquid. No air outside equals no pressure to push out the liquid, so no spray.
It might be argued that air trapped in the container would be at a higher pressure than vacuum, so push the liquid out anyway, but if it's that airtight it's probably going to swell up and pop like a balloon anyway.
It's ludicrously tiny compared to the rest of the dodgy science, but somehow it really bugged me. So my overall memory of that story will probably remain as "the one with the dodgy aerosol" which I'm sure is not what was intended.
later - numerous readers have pointed out that I've got it wrong and they did say that it didn't work in a vacuum - my attention must have wandered for a sec. Many apologies. I shall now brood about all the other dodgy science instead.
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no subject
Date: 2014-10-05 11:00 am (UTC)If it has a high vapour pressure then in a low pressure environment it's going to be boiling and out-gassing; perhaps enough to produce enough of a pressure head for a spray ...? (Trouble is, it would then vapourize once it left the nozzle. Not to mention freezing the container.)
Caveat: Not seen the episode in question.
no subject
Date: 2014-10-05 01:48 pm (UTC)