In this post I'll put questions that are bugging me, and their answers if I can find them.

A related post is my definitions of various things.

Q. Whose idea was it that ? should be the number of radians in a semi-circle (3.142) and not a whole circle? (6.284)

I don't know. It means that you have to double the value of ? when finding the diameter of a circle. But, you don't need to double it when finding the circle's area with the equation ?r². If ? equalled the radians in a circle the equation would be (?/2) r² instead. Maybe that's why.

Q. What's a steam turbine?

A fire heats steam, which turns blades and hence a rotor. Unbelievably this can move trains!

Also unlikely is that all power stations still rely on steam turbines. Even nuclear power stations - all that's different about them is they use nuclear fission as their heat source instead of coal.

This answer raises further questions: How is mechanical energy transfered to electrical energy? And do cars use a steam turbine?

Q. Why is unlocking mobile phones so popular?

In some shopping centres you can find a unscrupulous looking place (imho) which unlocks mobile phones. Up to now I thought unlocking a phone meant getting past the optional 4-digit password system. I was wrong; a phone is 'locked' when you can't switch its network provider. It's locked to that provider. It seems this is done so you're forced to carry out the contract length. Once the contract is over (after 12 months) you're legally allowed to unlock the phone, by getting a code from the provider.So why are there shops which unlock phones? Surely it's a simple matter of phoning your provider...?Source: MobileMentalism

Q. What is a punishment worse than hell?

As an atheist I don't believe in the horrible idea of hell. But I'll admit it's an interesting question to ask, what could be worse than hell?In hell, you bear only the punishment for your own sins. If you were to bear the sins of multiple people then this would (mathematically) be worse.In Dante's inferno, there's several levels in hell; the idea being (I think) is the punishments get worse as you go down. So being on a lower level of hell would be worse.In Angel (the Joss Whedon series), Gunn is trapped in a hell dimension, where he's tortured by a demon. But for some of the time in hell he's as a ordinary man, even with a (pretend) family. During this time his memory is wiped so he doesn't remember getting tortured. Later Gunn says that this part was worse than the torture, because of the pretence. Though I highly doubt that.

Q. How do you hold a guitar pick?

The best advice I've been given is to hold the pick like you're writing with it.

Before I look this up, I'd say it's made of tiny bits of shells and rocks? Wikipedia says it's tiny bits of rock.silt - 0.004mm to 1/16mmsand (grains) - or 1?16 mm to 2mmgravel - 2mm to 6.4cm(from wikipedia)

Q. Where do we get our days of the week from?

Sunday: sun day

Monday: moon day

Tuesday: Tyr's day

Wednesday: Odin's day

Thursday: Thor's day

Friday: Freya's day

Saturday: Saturn's day

The one I always forget is Tyr's day for Tuesday. Tyr was a norse god, like Odin, Thor and Freya, except less well-known. His most famous story was losing a hand to Fenrir the wolf. Maybe after Thor, Odin and Freya, there are no other main norse gods? Except for Odin, but he's a bastard so I can understand why we don't have a day of week named after him.