Physics Help needed

[Kandinsky]

Hey guys!
I am concerned about the accuracy marks in Paper 4. To what accuracy should we give the answer?
I had the same question in Paper 2, when I was advised to write answers to 3 s.f.
However, I encounter the answers in P4 which are of different accuracy, for example 1-2 s.f.
Can you help me please? Thanks

 

[momo_khan]

Assalamoalaikum Wr Wb

according to what we were taught you are supposed to choose the significant figures from the set of data. for example you have a distance of 13.0 cm and time of 2.2 seconds to calculate speed !

so the speed that you will calculate will be accurate to 2 significant figures. so what i am trying to say is that you will see how many significant figures are there in your data . if they are all upto 3 then you will give answers upto 3 sig fig but suppose you get a question with different significant figures so you will choose the least significant figures of the data which in the case of the above question was 2 !

hope you understood

 

[Kandinsky]

I understood. Thanks!
Then, could you look please at the question number 2
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s11_qp_42.pdf

The answer is 0.716 mol (3 s.f.), while the data is accurate to 2 s.f.
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s11_ms_42.pdf

How it can be explained?

 

[momo_khan]

indeed it is !
actually i don't know if you take chemistry or not but this is what i was taught in chemistry that you can round up moles only when the digit is 9 or 2 !

for example i can round up 0.719 to 0.72
and i can round up 0.711 to 0.71
and when it comes to 0.713 it will not be 0.71
so you can not round up 0.716 . you could have rounded it off if the 6 was replaced by a 2 or 9 .


hope you understood

 

[momo_khan]

Hey guys!
I am concerned about the accuracy marks in Paper 4. To what accuracy should we give the answer?
I had the same question in Paper 2, when I was advised to write answers to 3 s.f.
However, I encounter the answers in P4 which are of different accuracy, for example 1-2 s.f.
Can you help me please? Thanks

also please don't bother so much about the significant figures coz at the end it's your correct answer that really matters! also they will cut marks just once for the whole paper's significant mistakes !

 

[XPFMember]

also please don't bother so much about the significant figures coz at the end it's your correct answer that really matters! also they will cut marks just once for the whole paper's significant mistakes !

Aoa wr wb..

well..i don't think so..
Whatsoever, better you round it off...who knows that one mark gets your grade lowered...from an A* to an A...

Just remember,
your answer should have the same no. of s.f or one more than that of the least accurate figure of your data.

 

[momo_khan]

Aoa wr wb..

well..i don't think so..
Whatsoever, better you round it off...who knows that one mark gets your grade lowered...from an A* to an A...

Just remember,
your answer should have the same no. of s.f or one more than that of the least accurate figure of your data.

walaikum assalaam!
hmmmm true ....didn't think about that at all :/

 

[XPFMember]

walaikum assalaam!
hmmmm true ....didn't think about that at all :/

yup...do take care...after all, it's a simple thing...not a difficult one...then y ignore..

 

[momo_khan]

yup...do take care...after all, it's a simple thing...not a difficult one...then y ignore..

thanks for reminding bro !

 

[Kandinsky]

Thank you so much! Appreciate your help =)

 

[Kandinsky]

Oh, could someone please tell me one more thing)
as usual, the question is split into several parts.

For example, in part (a) the task is to show that some quantity(namely x) is 56 cm.
Then, part (b) says: find y, which is dependent on x. Then we use 56 cm, right?

and what if it is required in (a) to find x, and then in (b) using answer in (a) find y

if x = 2*pi*6.35 (for instance) cm = 39.9 cm
and y can be found from formula:
y = x^2 / 5.46, then should we substitute the exact value of x (i mean, find 2*pi*6.35, then square it and divide by 5.46) or use 39.9?

Thanks)

 

[momo_khan]

i think that if the first part is of prooving the answer then you can use that value ....if not then try using value that you got in your calculator for your next part if you have one !