Things you always wanted to know the answer to [Vol. 2]

[walm]

Warmfuzzies said:

Does everything in the universe have mass.

Nope. Light doesn't. (We're pretty sure...)

[Hugo a Gogo]

only catholics

[scarble]

^^ This guy

walm said:

Nope. Light doesn't. (We're pretty sure...)

Is it not more of a case as we're pretty sure it's ok to assume it doesn't, most of the time?
http://en.wikipedia.org/wiki/Photon#Contributions_...

[P-Jay]

GokTweed said:

TwigtheWonderkid said:

MarshPhantom said:

So it's to do with the sun being at angle and not directly overhead then, thanks very much for that.

If you think about it, the Antarctic is only about 6000 miles from equatorial Africa, so it would be very odd if a measly 6000 miles difference from an object 93,000,000 miles away could make the difference between 50c and -50c.

Even more odd, I seem to remember reading that the earth is actually closest to the sun in January and furthest away in June.

Yes, I heard that on Radio 2 the other evening - I suspect that is why Summers in the Southern Hemisphere are hotter then those up North.

Interesting bloke on the Radio who explained it all, explained that even though mid-winter passed us just before Xmas, we're really in the typically coldest part of the year now because there's a lot of lag in weather - it takes the oceans for example months to cool / heat up and being that we're surrounded by it, it plays a big part in UK weather - well that and the direction of the wind of course.

[Blib]

Why do some folk place their flat screen TVs high up on the wall, f'rinstance above the mantlepiece, when it's perfectly obvious that TVs are designed so that they are best viewed with the screen at eye level and looking up to see the TV is so damned uncomfortable in the first place?

Dur brains.

[Warmfuzzies]

scarble said:

Is it not more of a case as we're pretty sure it's ok to assume it doesn't, most of the time?
http://en.wikipedia.org/wiki/Photon#Contributions_...

Hmm, don't think that answered the question.... Surely no mass, wouldn't be affected by gravity...

[Hugo a Gogo]

Blib said:

Why do some folk place their flat screen TVs high up on the wall, f'rinstance above the mantlepiece, when it's perfectly obvious that TVs are designed so that they are best viewed with the screen at eye level and looking up to see the TV is so damned uncomfortable in the first place?

Dur brains.

cos you sit in your comfy chair and lean back a little, telly should lean forward slightly

(mine's not on the wall though)

[Blib]

Hugo a Gogo said:

Blib said:

Why do some folk place their flat screen TVs high up on the wall, f'rinstance above the mantlepiece, when it's perfectly obvious that TVs are designed so that they are best viewed with the screen at eye level and looking up to see the TV is so damned uncomfortable in the first place?

Dur brains.

cos you sit in your comfy chair and lean back a little, telly shouback a little.ld lean forward slightly

(mine's not on the wall though)

I'm sitting in my comfy chair now & I don't even need to lean back a little. Not one teeny bit.

[TwigtheWonderkid]

Bra sizes?? A double D is bigger than a D, double E is bigger than E etc. But double A is smaller than an A.

And I've never heard of double B or double C.

How's it work.

[WinstonWolf]

How come plaster saws don't cut the skin?

[Hugo a Gogo]

Blib said:

Hugo a Gogo said:

Blib said:

Why do some folk place their flat screen TVs high up on the wall, f'rinstance above the mantlepiece, when it's perfectly obvious that TVs are designed so that they are best viewed with the screen at eye level and looking up to see the TV is so damned uncomfortable in the first place?

Dur brains.

cos you sit in your comfy chair and lean back a little, telly shouback a little.ld lean forward slightly

(mine's not on the wall though)

I'm sitting in my comfy chair now & I don't even need to lean back a little. Not one teeny bit.

comfy straight-backed chair? horses for courses

'they' reckon 10 degrees up is ok

[GTIR]

Would there be anything left of an elephant if it was in the exhaust pit of the NASA's shuttle on a launch? (Assuming it wasn't blown out of the danger area)

Fully grown African male elephant for the pedants.

[craig_m67]

TwigtheWonderkid said:

Bra sizes?? A double D is bigger than a D, double E is bigger than E etc. But double A is smaller than an A.

And I've never heard of double B or double C.

How's it work.

Something to do with the angle of incidence perhaps?
(I dunno, been a long time between motor boats or punts)

[walm]

Warmfuzzies said:

scarble said:

Is it not more of a case as we're pretty sure it's ok to assume it doesn't, most of the time?
http://en.wikipedia.org/wiki/Photon#Contributions_...

Hmm, don't think that answered the question.... Surely no mass, wouldn't be affected by gravity...

You're into the realms of general relativity here which IMHO is infinitely more complicated than special relativity which is hardly Mickey Mouse.
However, the point with gravity is that it really bends space-time it doesn't just pull on things with mass.
Hence you have black holes and gravitational lensing both of which are gravity bending the normally straight trajectory of a photon.

[scarble]

Warmfuzzies said:

Hmm, don't think that answered the question.... Surely no mass, wouldn't be affected by gravity...

It wasn't meant to answer the question. Physics isn't about answers, it's about finding the next question

[LordGrover]

You are Brian Cox AICMFP.

[Blib]

How come a 'minus' times a 'minus' equals a 'plus' ?

[SpeckledJim]

Blib said:

How come a 'minus' times a 'minus' equals a 'plus' ?

I don't not know.

[SpeckledJim]

Because a minus multiplied by a plus is a minus. So a minus multiplied by a minus is the opposite of that.

seven -7s is -49. So -7 times -7 can only be 49.

[walm]

Blib said:

How come a 'minus' times a 'minus' equals a 'plus' ?

I think of it in terms of adding and subtracting things.

3*5 means we have 3 lots of 5 so it is 5+5+5 and = 15.

So 3*(-1) means we have THREE things and those things are minus ones: (-1) + (-1) + (-1) = -3.

What about multiplying something by -1?? <--------- this is the hard bit!!

Well that means instead of having ONE thing we have MINUS one of those things.
So say -1*5 means we have minus a five. i.e. -5.

We have something (multiplying by minus one) that means we are taking it away rather than adding it, if you like.
We turn the +5 into a -5 by multiplying by -1.

So what if we TOOK AWAY (i.e. multiplied by -1) a negative number???
Say (-1)*(-5)??

Well the rules don't change... in stead of having one of a "taking away number" (in this case minus 5) we are changing it into a "taking away a taking away number". Which is a rather long winded way to say ADDING!!

So we have taken away a taking away number. That's what happens when you multiply two negatives.