# PHYA5 ~ 20th June 2013 ~ A2 Physics Watch

Announcements

Report

#1181

(Original post by

Also, what are people thinking for the six markers for the core/astro papers?

I'm personally hoping for thermal derivation of the pV=1/3NM(crms)^2, cause its mentioned on the spec.

For astro stellar evolution wouldn't be too bad, or comparing the advantages/disadvantages of refracting & reflecting telescopes. Not sure what else is a potential question really...

**UnknownOrigin**)Also, what are people thinking for the six markers for the core/astro papers?

I'm personally hoping for thermal derivation of the pV=1/3NM(crms)^2, cause its mentioned on the spec.

For astro stellar evolution wouldn't be too bad, or comparing the advantages/disadvantages of refracting & reflecting telescopes. Not sure what else is a potential question really...

0

reply

Report

#1182

(Original post by

Help on June 12 part A 3)c) anyone? I'm stuck??

http://filestore.aqa.org.uk/subjects...1-QP-JUN12.PDF

http://filestore.aqa.org.uk/subjects...W-MS-JUN12.PDF

**Science211**)Help on June 12 part A 3)c) anyone? I'm stuck??

http://filestore.aqa.org.uk/subjects...1-QP-JUN12.PDF

http://filestore.aqa.org.uk/subjects...W-MS-JUN12.PDF

C=k/x^2

find k from the original Count rate=0.62 and distance, the rest follows.

0

reply

Report

#1183

It's not a sig fig question so you shouldn't worry too much, sometimes they'll even put the non rounded figure in brackets in the mark scheme like: 9.2 (9.15) but to be on the safe side just try to do the minimum sig figs in the question

Another similar thing is, when they say something like "Show x is about 5" so you show it equals to 4.9 and then in the next part you have to do a calculation with that number, do you use 5 or 4.9? My teacher said 4.9 but the mark schemes tend to use 5 :/

0

reply

Report

#1184

(Original post by

paper was really easy to be honest. but i screwed. :/

**iwantopas19**)paper was really easy to be honest. but i screwed. :/

Quite a few I couldn't attempt

2 scientist names : kukele & "Paul"

I don't know who paul was, but just sounded like a chemist's typical name to me at the time -_-

0

reply

Report

#1185

Is latent heat absorbed by the other mass? I'm guessing not but then what exactly happens to it?

Posted from TSR Mobile

Posted from TSR Mobile

0

reply

Report

#1186

(Original post by

I try to do this anyway but when I'm marking my own papers it gets a bit ambiguous Thanks!

Another similar thing is, when they say something like "Show x is about 5" so you show it equals to 4.9 and then in the next part you have to do a calculation with that number, do you use 5 or 4.9? My teacher said 4.9 but the mark schemes tend to use 5 :/

**Matt III**)I try to do this anyway but when I'm marking my own papers it gets a bit ambiguous Thanks!

Another similar thing is, when they say something like "Show x is about 5" so you show it equals to 4.9 and then in the next part you have to do a calculation with that number, do you use 5 or 4.9? My teacher said 4.9 but the mark schemes tend to use 5 :/

**about**5" I use the raw value because know we both know it's not actually 5, it's just around 5.

I do usually try it with the rounded value and see if I get the same answer (which it usually is anyway to about 2-3 s.f.) so it would end up not mattering. Then again, that's just me so if the mark schemes are using rounded values, go for it

0

reply

Report

#1187

(Original post by

Use

C=k/x^2

find k from the original Count rate=0.62 and distance, the rest follows.

**jarasta**)Use

C=k/x^2

find k from the original Count rate=0.62 and distance, the rest follows.

0

reply

Report

#1188

(Original post by

Is latent heat absorbed by the other mass? I'm guessing not but then what exactly happens to it?

Posted from TSR Mobile

**cooldudeman**)Is latent heat absorbed by the other mass? I'm guessing not but then what exactly happens to it?

Posted from TSR Mobile

If something is being cooled down & the heat is going towards something else to reach thermal equilibrium then some of the heat given may be latent heat, that is if the cooling substance changes state ofcourse

0

reply

Report

#1189

Hey, on the June 2010 astro paper, q 2b ii) has stumped me.

It asks to calculate the difference in brightness of 2 stars (show that it's 8000)

the mark scheme says:

difference in magnitude = 9.8

so difference in brightness = 2.5^9.8

just want to know, where did this 2.5 come from?

It asks to calculate the difference in brightness of 2 stars (show that it's 8000)

the mark scheme says:

difference in magnitude = 9.8

so difference in brightness = 2.5^9.8

just want to know, where did this 2.5 come from?

0

reply

Report

#1191

(Original post by

What do you mean other mass ?

If something is being cooled down & the heat is going towards something else to reach thermal equilibrium then some of the heat given may be latent heat, that is if the cooling substance changes state ofcourse

**posthumus**)What do you mean other mass ?

If something is being cooled down & the heat is going towards something else to reach thermal equilibrium then some of the heat given may be latent heat, that is if the cooling substance changes state ofcourse

Posted from TSR Mobile

0

reply

Report

#1192

(Original post by

Hey, on the June 2010 astro paper, q 2b ii) has stumped me.

It asks to calculate the difference in brightness of 2 stars (show that it's 8000)

the mark scheme says:

difference in magnitude = 9.8

so difference in brightness = 2.5^9.8

just want to know, where did this 2.5 come from?

**miike183**)Hey, on the June 2010 astro paper, q 2b ii) has stumped me.

It asks to calculate the difference in brightness of 2 stars (show that it's 8000)

the mark scheme says:

difference in magnitude = 9.8

so difference in brightness = 2.5^9.8

just want to know, where did this 2.5 come from?

Hope that helps.

1

reply

Report

#1193

So after 30 seconds, the total amount of energy applied to the ice is:

98x30= 2940 Joules.

We know that the temp change is 14 as it goes from -14 degrees to 0.

Then we can use the equation E = mc(delta)T and rearrange to find c, the specific heat capacity.

c = E/m(delta)T

so

c = 2940/ (0.1 x 14) = 2100 J kg^-1 K-1

the mass has to be in kg so convert 100g = 0.1kg

and the

**change**in temp is the same whether Kelcvin or Celcius

*edit* I did the wrong question didn't I? ¬.¬

gahh, well, more practise for me I guess..

0

reply

Report

#1194

(Original post by

A magnitude 1 star is 2.5x brighter than a mag 2 star. Each magnitude class is 2.5 times brighter than the previous one. So as there is a difference to 9.8 for the magnitude, the ratio of brightness is 2.5^9.8.

Hope that helps.

**amish123**)A magnitude 1 star is 2.5x brighter than a mag 2 star. Each magnitude class is 2.5 times brighter than the previous one. So as there is a difference to 9.8 for the magnitude, the ratio of brightness is 2.5^9.8.

Hope that helps.

I'm so screwed for astro.

I'm okay on topics 9-11, but astro just kills me.

0

reply

Report

#1195

(Original post by

Okay so the question says 98 J are delivered each second.

So after 30 seconds, the total amount of energy applied to the ice is:

98x30= 2940 Joules.

We know that the temp change is 14 as it goes from -14 degrees to 0.

Then we can use the equation E = mc(delta)T and rearrange to find c, the specific heat capacity.

c = E/m(delta)T

so

c = 2940/ (0.1 x 14) = 2100 J kg^-1 K-1

the mass has to be in kg so convert 100g = 0.1kg

and the

*edit* I did the wrong question didn't I? ¬.¬

gahh, well, more practise for me I guess..

**miike183**)Okay so the question says 98 J are delivered each second.

So after 30 seconds, the total amount of energy applied to the ice is:

98x30= 2940 Joules.

We know that the temp change is 14 as it goes from -14 degrees to 0.

Then we can use the equation E = mc(delta)T and rearrange to find c, the specific heat capacity.

c = E/m(delta)T

so

c = 2940/ (0.1 x 14) = 2100 J kg^-1 K-1

the mass has to be in kg so convert 100g = 0.1kg

and the

**change**in temp is the same whether Kelcvin or Celcius*edit* I did the wrong question didn't I? ¬.¬

gahh, well, more practise for me I guess..

Posted from TSR Mobile

0

reply

Report

#1196

astrophysics related

can spherical aberration be completely eliminated by using parabolic mirrors?

can spherical aberration be completely eliminated by using parabolic mirrors?

0

reply

Report

#1197

(Original post by

astrophysics related

can spherical aberration be completely eliminated by using parabolic mirrors?

**Jack93o**)astrophysics related

can spherical aberration be completely eliminated by using parabolic mirrors?

Yes.

0

reply

Report

#1198

(Original post by

I can't be certain, but I'm fairly certai you won't be getting a question on the gas law derivation directly. They do the six-marker tiered - you can't really tier a derivation, and it's too long to do as a "short" question.

**Thr33**)I can't be certain, but I'm fairly certai you won't be getting a question on the gas law derivation directly. They do the six-marker tiered - you can't really tier a derivation, and it's too long to do as a "short" question.

I can't really think what they could ask thermal side?

Unless its a nuclear question... although if it was something like discuss the principle features of a nuclear reactor which enable it to operate safely or something I wouldn't be fussed cause I find that pretty straightforward.

0

reply

Report

#1199

What does the gradient of an activity - time graph represent? (Like the tangental gradient?)

0

reply

Report

#1200

(Original post by

Ah I see where you're coming from with the tier thing. Damn.

I can't really think what they could ask thermal side?

Unless its a nuclear question... although if it was something like discuss the principle features of a nuclear reactor which enable it to operate safely or something I wouldn't be fussed cause I find that pretty straightforward.

**UnknownOrigin**)Ah I see where you're coming from with the tier thing. Damn.

I can't really think what they could ask thermal side?

Unless its a nuclear question... although if it was something like discuss the principle features of a nuclear reactor which enable it to operate safely or something I wouldn't be fussed cause I find that pretty straightforward.

0

reply

X

### Quick Reply

Back

to top

to top