Why a shower curtain clings
QUESTION Why do shower curtains have an annoying habit of billowing in, even when windows and doors are closed? This is an example of Bernoulli’s Equation, which states that when a fluid is accelerated, its static pressure drops, noting that both water and air act as fluids.
in an enclosed shower, the air volume within the enclosure is partially sealed from the greater air volume of the room, forming two discrete atmospheres.
The seal is f ormed via the impermeability of the curtain fabric, but is only partial, due to the gaps around the rails and edges.
Once the shower is turned on, with its relatively high velocity water flow from the shower head, under pressure, the accelerated volume of water inside the shower enclosure causes a small local drop in atmospheric pressure in the partially sealed area.
so the curtain is sucked into the enclosure, rather than blown in from outside.
if you use a shower curtain that runs along only one edge of a bathtub, the effect i s greatly reduced, as the two compartments can equalise pressure more easily.
Nick Briody, Henfield, West Sussex.
QUESTION In the final episode of Downton Abbey, a character was diagnosed with pernicious anaemia and preparing to die. When was vitamin B12 treatment discovered and used for this condition? FurThEr to the earlier answer, when my brother was born in 1939, our mother developed pernicious anaemia. Taken to our local cottage hospital, she was told to eat halfa-pound of raw liver a day to cure her illness. she said she couldn’t face it, even if her life depended on it which, of course, it did.
Our GP, Dr Graham stenhouse, obtained an extract of liver that could be administered by injection. Mother had a course of injections that cured the anaemia and brought her back to good health — Dr stenhouse saved her life.
Although in those pre-Nhs days, the cost of the treatment was borne by the Friendly society, to which we contributed, my father was expected to pay f or the hospital stay, which came to £25, a huge amount for a working man.
Dad earned £2 a week, of which £1 went on food and coal, plus six shillings for rent, so there was little left for anything else. i recall him saying: ‘We will just have to worry about it when the bill comes in.’
When it came in, the bill was just 25 shillings. Why that was, and who paid the rest, we never found out.
Dennis Haynes, Faringdon, Oxon.