National 5 Physics: Calculations HELP

After doing my prelim in March and getting a high B I realised the main reason for losing marks was because I was not rounding my final answer in calculations properly. I am still having some trouble with this as I don't know how many significant figures an answer should be rounded to. The exam is in about a few weeks time and I need to learn this very quickly.

Thanks.

Reply 1

MartinDUFC

2

I believe the standard is 3 Sig Figs, however if you are in doubt use the same amount of sig figs as provided in the question and that way you can't go wrong :smile:

Reply 2

Ethan100

OP

15

Original post by MartinDUFC

I believe the standard is 3 Sig Figs, however if you are in doubt use the same amount of sig figs as provided in the question and that way you can't go wrong :smile:

Oh alright,

so for example if I need to use the numbers "22" and "202" in my calculation , then have my final answer to 2 sig figs ?

Thanks :smile:

Reply 3

MartinDUFC

2

Original post by Ethan100

Oh alright,

so for example if I need to use the numbers "22" and "202" in my calculation , then have my final answer to 2 sig figs ?

Thanks :smile:

Would probably depend on the context of the question, but I would still say 3 seeing as 202 is 3 sig figs.

Reply 4

Ethan100

OP

15

Original post by MartinDUFC

Would probably depend on the context of the question, but I would still say 3 seeing as 202 is 3 sig figs.

Thanks Martin for the help, I just need to do some practice and I think I will get it. Are you also doing nat 5 ?

Reply 5

Patrick.Williams

The way I was taught was to use the least accurate number from the question as your answer can't be more accurate than the quantities you are provided.

Reply 6

MartinDUFC

2

Original post by Ethan100

Thanks Martin for the help, I just need to do some practice and I think I will get it. Are you also doing nat 5 ?

No problem, I'm actually doing Advanced Higher this year, exam is still a few weeks away though so got a bit of time on my side. http://mrmackenzie.co.uk/ is an excellent resource for notes + past papers. I used it for nat 5,Higher and advanced higher and achieved good results with it. My advice would be (as boring as it is) just complete as many past papers as you can. If there's an area that you're struggling with, go back to your class notes and try to make sure you understand the concepts involved fully rather than just trying to get a one-off answer, this way you'll be able to tackle any problem you come across :smile:

Good luck with your exam, don't worry about prelim results as well - i got a C in both my Nat 5 and higher physics prelims, but still managed to get an A in both of the final exams, i'm sure you'll do well.

Reply 7

Ethan100

OP

15

Original post by MartinDUFC

No problem, I'm actually doing Advanced Higher this year, exam is still a few weeks away though so got a bit of time on my side. http://mrmackenzie.co.uk/ is an excellent resource for notes + past papers. I used it for nat 5,Higher and advanced higher and achieved good results with it. My advice would be (as boring as it is) just complete as many past papers as you can. If there's an area that you're struggling with, go back to your class notes and try to make sure you understand the concepts involved fully rather than just trying to get a one-off answer, this way you'll be able to tackle any problem you come across :smile:

Good luck with your exam, don't worry about prelim results as well - i got a C in both my Nat 5 and higher physics prelims, but still managed to get an A in both of the final exams, i'm sure you'll do well.

Wow I really appreciate it, hahah. You just provided me with so much motivation, Good luck with advanced higher, wish you only the best,

Reply 8

Hey234

10

Original post by Ethan100

Thanks Martin for the help, I just need to do some practice and I think I will get it. Are you also doing nat 5 ?

I am so nervous about open ended question, hopefully it won't be too difficult.

Reply 9

Ethan100

OP

15

Original post by Hey234

I am so nervous about open ended question, hopefully it won't be too difficult.

Yeah me tooo :frown:

Hopefully the sqa are nice with this exam

If you have any questions come ask them in the physics 2016 nat 5 thread.

http://www.thestudentroom.co.uk/showthread.php?t=4080705&page=15&p=65060289#post65060289

Reply 10

Hey234

10

Sqa 2014 paper 2 qu2 need help please

Reply 11

A+Hunter

9

Original post by Hey234

Sqa 2014 paper 2 qu2 need help please

That question is about voltage dividers. You can do them in a number of ways, But this is how I like to do it:

They've given you the resistance of component 1 (the variable resistor) as 1050 ohms
So mark that down as R1= 1050

They've NOT given you the resistance of component 2 (the thermistor), as this is what you're trying to find.
So R2 = ?

They've said that the voltage across the Thermistor is 2V, But you don't know the voltage across the FIRST component in the circuit (The variable resistor).
So V2 (Voltage of thermistor) = 2v

The way you work out the voltage of the variable resistor is by simply taking away the voltage supply by the voltage of the thermistor.
So V1 = Vs - V2 = 5-2= 3v

Now you can use the following equation which can be found in the data book:
V1/V2 = R1/R2

Just plug in the numbers now and solve for R2... So:
3/2 = 1050/R2
1.5 = 1050/R2
R2 = 1050/1.5
R2 = 700 Ohms.

Hope it helped. If you need help for the other parts just let me know.

National 5 Physics: Calculations HELP

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