You are Here: Home

# National 5 Physics 2015-2016

Announcements Posted on
Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher! 27-10-2016
1. (Original post by sameehaiqbal)
Is the change in temperature of the Eh=cmDelta measured in Degrees or Kelvin ?
2. (Original post by Ethan100)
Is the change in temperature of the Eh=cmDelta measured in Degrees or Kelvin ?
Degrees

Kelvin is for gas equations
3. (Original post by Ethan100)
Is the change in temperature of the Eh=cmDelta measured in Degrees or Kelvin ?
Well normally degrees.

To convert from celcius to kelvin: add 273
To convert from kelvin to celcius: subtract 273

Example: 5 degrees is 278 kelvin
Example: 5 kelvin is -268 degrees
4. (Original post by A+Hunter)
Degrees

Kelvin is for gas equations
Thanks man
5. (Original post by Ethan100)
Heyyyyy
I'm doing alright I guess, I think I may have left the revision too late.
Too much to go over but not much time.

Do you recommend Bbc bitesize quizzes as revision or no ?
I recommend you check out the course notes and ONLY revise what there asking you to in the course notes, if you're running low on time:

http://www.sqa.org.uk/files_ccc/CfE_...es_Physics.pdf

This has helped me a lot for revising Unit 1 (Unit 3 in my case) which is Electricity and Energy.
6. Gravity is 9.8 and not 10 right ? Some old exam questions use 10 as gravity, should I be doing that to ?
7. (Original post by Ethan100)
Gravity is 9.8 and not 10 right ? Some old exam questions use 10 as gravity, should I be doing that to ?
Always use 9.8.

Yeah some Int2 and Credit use 10, But use 9.8 regardless unless the question explicitly states to use 10
8. In the gas laws calculation what should the units of V be ? cm cm^3 or m^3 ?
Oh and the same for Area ? when using P=F/A
9. (Original post by Ethan100)
In the gas laws calculation what should the units of V be ? cm cm^3 or m^3 ?
Oh and the same for Area ? when using P=F/A
the volume add ^3 (cubed) at the end. It doesnt have to be CM's. Can be litres etc

The area is ^2 (squared)
10. Doing some gas calculations and I'm a little confused as to why the answer in the textbook is 150,000Pa when my answer is completely different.

The gas in a cylinder is at a pressure of 120,000Pa and occupies a volume of 18cm^3. The cylinder is compressed to a volume of 14cm^3. The temperature is kept constant. Calculate the new pressure.

I use the formula P1V1=P2V2
120,000 x 18 = p2 x 14
2160000 = p2 x 14
2160000/14 = p2
p2 = 154285.714285

What do I do here to get the answer 150,000Pa? Or is my calculation wrong? Do I need to round or something? So confused. This is probably stupid question. Lol. Somebody help please

Much appreciated

The answer in the textbook is P2 = 154000 = 150000 Pa??????????
11. (Original post by sameehaiqbal)
Doing some gas calculations and I'm a little confused as to why the answer in the textbook is 150,000Pa when my answer is completely different.

The gas in a cylinder is at a pressure of 120,000Pa and occupies a volume of 18cm^3. The cylinder is compressed to a volume of 14cm^3. The temperature is kept constant. Calculate the new pressure.

I use the formula P1V1=P2V2
120,000 x 18 = p2 x 14
2160000 = p2 x 14
2160000/14 = p2
p2 = 154285.714285

What do I do here to get the answer 150,000Pa? Or is my calculation wrong? Do I need to round or something? So confused. This is probably stupid question. Lol. Somebody help please

Much appreciated

The answer in the textbook is P2 = 154000 = 150000 Pa??????????
I just did the question and got the same answer as you. I think it's just that they have rounded it to 2 significant figures because V1 and V2 have 2 sig figs. I'm not totally sure though.
12. (Original post by sameehaiqbal)
Doing some gas calculations and I'm a little confused as to why the answer in the textbook is 150,000Pa when my answer is completely different.

The gas in a cylinder is at a pressure of 120,000Pa and occupies a volume of 18cm^3. The cylinder is compressed to a volume of 14cm^3. The temperature is kept constant. Calculate the new pressure.

I use the formula P1V1=P2V2
120,000 x 18 = p2 x 14
2160000 = p2 x 14
2160000/14 = p2
p2 = 154285.714285

What do I do here to get the answer 150,000Pa? Or is my calculation wrong? Do I need to round or something? So confused. This is probably stupid question. Lol. Somebody help please

Much appreciated

The answer in the textbook is P2 = 154000 = 150000 Pa??????????
(Original post by Ethan100)
I just did the question and got the same answer as you. I think it's just that they have rounded it to 2 significant figures because V1 and V2 have 2 sig figs. I'm not totally sure though.
You need to round your answers between 1-4 sig figs (I would do 3).

The SQA will not accept long answers like that.

So 154285.714285 should be rounded to 2 sigs or 3 sigs.

Also you need to be fully aware of how to use scientific notation, Because sometimes your answers should be put into scientific notation. Once again if you don't do this they won't give you the final mark.
13. (Original post by A+Hunter)
You need to round your answers between 1-4 sig figs (I would do 3).

The SQA will not accept long answers like that.

So 154285.714285 should be rounded to 2 sigs or 3 sigs.

Also you need to be fully aware of how to use scientific notation, Because sometimes your answers should be put into scientific notation. Once again if you don't do this they won't give you the final mark.
Can SQA ask us to rearrange the equation and find e.g volume instead?
Or is that unlikely?
Thanks for your help x
14. (Original post by A+Hunter)
You need to round your answers between 1-4 sig figs (I would do 3).

The SQA will not accept long answers like that.

So 154285.714285 should be rounded to 2 sigs or 3 sigs.

Also you need to be fully aware of how to use scientific notation, Because sometimes your answers should be put into scientific notation. Once again if you don't do this they won't give you the final mark.
Thanks for that. Fortunately i'm pretty confident with scientific notations
15. Wait so if I got an answer of 974934525
and then rounded it to 3 sig figs so it would be : 975000000
I would still get it wrong if I didn't put it as 9.75x10^8 ? or even 975M ?
16. (Original post by sameehaiqbal)
Can SQA ask us to rearrange the equation and find e.g volume instead?
Or is that unlikely?
Thanks for your help x
Yes of course lol.

They can expect you to rearrange equations where necessary

(Original post by sameehaiqbal)
Thanks for that. Fortunately i'm pretty confident with scientific notations
Nice.

(Original post by Ethan100)
Wait so if I got an answer of 974934525
and then rounded it to 3 sig figs so it would be : 975000000
I would still get it wrong if I didn't put it as 9.75x10^8 ? or even 975M ?

If you got something like 37400000 I would put it in scientific notation (3.74x10^7)

If however you got something like this:
549271 I would then round it between 1-4 sig figs. (54900 3 sig figs)
17. Also here is another silly question:

Say your answer was like 250,000 and it asked you to put it in scientific notation

Possible notations could be 25x10^4
or
2.5x10^5

They all represent 250,000

Can you just use either one? Lmao

Edit: Really just want to be on the safe side...
18. (Original post by sameehaiqbal)
Nooo of course not! It's only in situations where they explicitly ask you to put it in scientific notation. I.e "Give your answer in scientific notation" xx
No they expect you to put numbers that are big in scientific notation or round them.

It depends. See the above post
19. (Original post by A+Hunter)
No they expect you to put numbers that are big in scientific notation or round them.

It depends. See the above post

Ah okay cheers xx
20. (Original post by sameehaiqbal)
Also here is another silly question:

Say your answer was like 250,000 and it asked you to put it in scientific notation

Possible notations could be 25x10^4
or
2.5x10^5

They all represent 250,000

Can you just use either one? Lmao

Edit: Really just want to be on the safe side...
From the Marking schemes the SQA like things with decimals in them lol So I'd go with 2.5 However I can't see why they'd mark you down for the other one

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
your full birthday is required
1. Oops, you need to agree to our Ts&Cs to register

Updated: August 27, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### University open days

Is it worth going? Find out here

### How to cope with a heavy workload

Poll
Applying to university

### Find your perfect match

Our tool will help you find the perfect uni course for you

## Make your revision easier

Don't miss out on a place at uni - get clearing email alertsStudy Help rules and posting guidelines

## Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.