These answers can be found just by Googling, but it’s nice to have a record of things I’ve wondered about.
Why do jetskis spit that jet of water vertically?
This is apparently just for visibility, there is a little pipe attached to the outlet that faces upward. A lot of people plug it so they don’t spray passengers or nearby people.
Why is orange juice usually from concentrate?
Easier to package and transport.
Why do American school buses look more or less identical?
Road rules are different around school busses; in particular, the stop sign that pops out from the side stops traffic in both directions. For this reason it is important that they are easily identifiable. The yellow is said to be more eye-catching in peripheral vision than other colours.
What are blackboards made of?
These days, porcelain enamel on a steel base. They are often green rather than black, the thinking being that the green paint reduces glare compared to black.
What are the square, Asian-looking stamps sometimes present on the title page of old books?
Those are ‘seals’, signatures in stamp form. The books I’m thinking of must have once been owned by someone who had their own seal.
What is the connection between barbers and red/white striped poles?
One of the services that medieval “barber-surgeons” would perform was blood-letting. The pole represents the staff that patients would grip to make their veins pop, and the red and white colouring represents the bloody bandages that would be hung outside the shop to dry.
Why do signs give the maximum fine for disobeying them? Wouldn’t a minimum be more persuasive?
Typically people are given the maximum penalty, so the value shown is the fine that any would-be lawbreakers should expect. However, it is better for judges to be able to use discretion on exactly what fine is imposed in specific situations.
Why do so many recipe websites have long boring stories before the recipes?
Some people like to waffle, but a big reason is ad revenue and SEO. Long and detailed text causes visitors to spend more time on your site, and gives more opportunities to include relevant search keywords.
Were people just killed by acute appendicitis before modern surgery?
Yes.
Why are bay leaves typically not ground up like other herbs?
The flavour of bay leaves is overpoweringly strong when ground up, even in very small amounts.
What is the cause of the ‘fingernails on a blackboard’ response?
The cause is currently unknown, but there are some theories.
One hypothesis is that the sound is similar to the alarm call of some monkeys and the instinct to cringe dates back to early human evolution. Another is that the sound is “the ultimate dissonance”, and is unpleasant for the same reason that dissonant music is unpleasant.
Interestingly, tests showed that it is the middle frequencies (2000Hz to 4000Hz) that cause the instinctive reaction, not the high frequencies as one might expect.