AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread]

will there be any model answers for section A??

Also for the questioon that said to right two thinngs to make the sentence about volume being inversely proportionl to pressure; did anyone say mass of the gas? I couldnt think of another one so thats what i put down

I said tempreture and moles have to be consatnt, is that right

??

Reply 841

CourtlyCanter

8

Original post by boyyo

will there be any model answers for section A??

Also for the questioon that said to right two thinngs to make the sentence about volume being inversely proportionl to pressure; did anyone say mass of the gas? I couldnt think of another one so thats what i put down

1. Under the same temperature.
2. The mass of the ideal gas must have the same mass. (ie. constant mass)

Reply 842

Yo12345

2

Density was 2 x 10^-24

Posted from TSR Mobile

Reply 843

-jordan-

5

Original post by Mango Milkshake

I said tempreture and moles have to be consatnt, is that right

??

Yes, because if the number of moles is constant then so is mass.

Reply 844

Amy-Jo

10

I put elastic collisions

Reply 845

marioman

8

Original post by Amy-Jo

I put elastic collisions

That's already assumed because the question said "ideal gas".

Reply 846

boyyo

6

Original post by Mango Milkshake

I said tempreture and moles have to be consatnt, is that right

??

erm idk i put constant mass

Reply 847

Yo12345

2

Original post by boyyo

erm idk i put constant mass

Same thing. Correct

Posted from TSR Mobile

Reply 848

tanyapotter

20

what was the density of the gas?
i got 1.2 something?

Reply 849

HughBax

Original post by Jon1234321

I also got 1.2x10^8 AU for the penultimate quasar question but starting to think this is wrong after looking on here :frown:

For those who got the other answer (2.4 something) could you tell me how u did this question as i am really confused.

I can't remember the values they gave us but it was like, intensity of sunlight at earth is X times greater than light intensity from the Quasar and the Quasar is Y times brighter than the sun.

So I set up the equations using inverse square law

Sunlight intensity at Earth: 1 x 1/(1AU)^2
Quasar intensity at Earth Y x 1/d^2 = 1/X
Then rearrange to make d the subject

Its hard for me to properly explain it, but I'm basically making the Sun a standard with its light intensity at Surface of Earth and power =1
so intensity of Quasar at Earth is Intensity of Sunlight at Earth/X
brightness of Quasar is Y

When I say Brightness I mean light intensity at the Sun or At the Quasar or there power output or whatever. I don't need to know that anymore anyway.

A lot of that may not make the most sense and it may not help much but I'm pretty sure I did something like that.

Reply 850

username1967507

11

Original post by FireBLue97

1.8x10^4 -1.5510x10^4 gives 2.1x10^3
next part 2.5x10^4

1.8x10^4-1.55x10^4 gives 2.5x10^3 lol?

next part is 2.1x10^3

Reply 851

crashMATHS

16

Original post by boyyo

will there be any model answers for section A??

Also for the questioon that said to right two thinngs to make the sentence about volume being inversely proportionl to pressure; did anyone say mass of the gas? I couldnt think of another one so thats what i put down

Constant temperature
Closed system

Reply 852

Yo12345

2

Original post by tanyapotter

what was the density of the gas?
i got 1.2 something?

2 x 10^-24

Posted from TSR Mobile

Reply 853

HughBax

Original post by boyyo

erm idk i put constant mass

I think both mass or moles is right

Reply 854

username1967507

11

Original post by tanyapotter

what was the density of the gas?
i got 1.2 something?

yeah density was either 1.20 or 1.21 depending on what you did

Reply 855

txnilxnur

2

Original post by tanyapotter

what was the density of the gas?
i got 1.2 something?

yeah I got that too.

Seemed to be a lot of small answers like i remember getting 0.06 and some others like that

Reply 856

username1967507

11

Original post by Yo12345

2 x 10^-24

Posted from TSR Mobile

dont think this is right

Reply 857

TajwarC

17

Original post by tanyapotter

what was the density of the gas?
i got 1.2 something?

I got 1.2kgm^-3 I think

Reply 858

FireBLue97

2

Original post by Yo12345

2 x 10^-24

Posted from TSR Mobile

1.2 i think

Reply 859

TajwarC

17

What was the moles of gas? I got 0.067 or 0.0016/0.024. Then used mass is molesxmolar mass to get the mass of air, then density over the volume from the previous part of the question

And I used pV=NkT for the volume, because it didn't give the moles initially

AQA Physics PHYA5 - 28th June 2016 [Exam Discussion Thread]

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