# PHYA5 ~ 20th June 2013 ~ A2 PhysicsWatch

Announcements
6 years ago
#1001
Can anyone explain question 2cii from the June 2012 paper?

Looks really simple but I don't get it D:
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6 years ago
#1002
(Original post by Lepton)
I'm nervous... anyone else nervous?!
Just a little. I really really want to do well on this exam (more so than any other exam I've sat this time around) so that's probably contributing to it
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6 years ago
#1003
(Original post by cameron95)
If anyone's doing astrophysics can they help me with a minor query with the H-R diagram. The following diagram (page 30) is the version given in the specification, but I'm not sure about the values on the temperature/class axis. Is each letter at the centre of the class, or is it the space to right (or even to the left)? Thanks in advance.

http://filestore.aqa.org.uk/subjects...-W-TRB-OGA.PDF
At the centre of each class.
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6 years ago
#1004
(Original post by Beth_L_G)
Can anyone explain question 2cii from the June 2012 paper?

Looks really simple but I don't get it D:
It really is simple & took me a while to figure out how simple it was... after doing all sorts of funky stuff with that exponential formula

You started off with 3 x 10^22 atoms... you want to know how many Uranium atoms there are... 2/3 of this are uranium atoms. So just multiply
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6 years ago
#1005
astrophysics related....

is the red shift of a galaxy (or whatever) due to its actual movement relative to us on earth, OR is it due to the expansion of space in the universe

**** I'm getting sooo confused, apparently theres 'cosmological red shift'?
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6 years ago
#1006
(Original post by bugsuper)
Just a little. I really really want to do well on this exam (more so than any other exam I've sat this time around) so that's probably contributing to it
Yeah, I'm exactly the same, this is the exam I've been thinking about for the longest, it's also my last which is nice!

It will be a lovely paper I'm sure! Good luck!
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6 years ago
#1007
(Original post by D4rth)
Yea I think the mark scheme had a mistake. Nucleon number should be the same.

Posted from TSR Mobile
Right!? Other people must have done that paper and realised the same mistake....
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6 years ago
#1008
(Original post by Jack93o)
astrophysics related....

is the red shift of a galaxy (or whatever) due to its actual movement relative to us on earth, OR is it due to the expansion of space in the universe

**** I'm getting sooo confused, apparently theres 'cosmological red shift'?
Yeah, red shift is due to relative recessive velocity between the source and the observer. This recessive velocity is caused by the Universe expanding, which is thought to be driven by some 'dark energy'.
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6 years ago
#1009
(Original post by sw121)
I was reading the astro notes on the aqa website.

it says the absolute magnitude of Antares is -5.3 and absolute magnitude of Proxima century is 15. Both the stars have the same black-body temperature.

according to them the diameter of Antares is 5500 times that of Proxia century.

i did (2.512^20.3)^1/2 and i get the diameter ratio as 11487 times.

can someone please explain how it's 5500
I agree with your working out, I can't seem to get their answer.
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6 years ago
#1010
(Original post by iwantopas19)
haha hey posthumus! I can find u everywhere
Lol hey, hope your chem went well Not sure if our papers were exactly the same, but I got owned!

Time to get cracking with unit 5..
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6 years ago
#1011
What has been the highest full ums boundary?

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6 years ago
#1012
(Original post by posthumus)
Lol hey, hope your chem went well Not sure if our papers were exactly the same, but I got owned!

Time to get cracking with unit 5..
I know I see you all the time. Not literally -_-

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6 years ago
#1013
Does anyone doing astrophysics understand june 2012 2bii well. Well enough to explain t to me?
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6 years ago
#1014
(Original post by amish123)
At the centre of each class.
Yeah I thought it must be. Cheers.
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6 years ago
#1015
(Original post by Beth_L_G)
Does anyone doing astrophysics understand june 2012 2bii well. Well enough to explain t to me?
imagine theres a right angle triangle

the long baseline is the distance between earth and the star

the smallest side is the distance between the star and the exoplanet

and the hypotenuse is the distance between earth and the exoplanet

the angle is you're looking for, is between the hypotenuse and the long baseline of the triangle

so say the angle is x

tan x = distance between star and the exoplanent / distance between earth and the star (10.5 light years)

because the angle is very small

tan x = x (in radians)

so you don't need to invert tan
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6 years ago
#1016
(Original post by Jack93o)
imagine theres a right angle triangle

the long baseline is the distance between earth and the star

the smallest side is the distance between the star and the exoplanet

and the hypotenuse is the distance between earth and the exoplanet

the angle is you're looking for, is between the hypotenuse and the long baseline of the triangle

so say the angle is x

tan x = distance between star and the exoplanent / distance between earth and the star (10.5 light years)

because the angle is very small

tan x = x (in radians)

so you don't need to invert tan
I love you!
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6 years ago
#1017
(Original post by cooldudeman)
I know I see you all the time. Not literally -_-

Posted from TSR Mobile
aha Are you doing turning points? If so, you might want to follow this too :

http://www.thestudentroom.co.uk/show....php?t=2382437
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6 years ago
#1018
(Original post by posthumus)
aha Are you doing turning points? If so, you might want to follow this too :

http://www.thestudentroom.co.uk/show....php?t=2382437
Yhh turning points. Its nice. And will do.

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6 years ago
#1019
guys... how do you obtain this graph...
really confused.. com
what equation would u use;
its on june 12 paper question 5a.
like whats the equation of the graph
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6 years ago
#1020
Is total ke of gas molecules different to total ke of moles????

Help

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