Significant Figures (PHYSICS 'O')
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I know that for all physics question final answer must leave in 3 sig.fig.
However, intermediate workings can leave in fraction form? Or if there is no fraction can leave in 4 sig. fig to maintain accuracy?
A lot of times i use the calculator answer to continue calculation. However, a lot of answer keys round off the intermediate working to 3 sig. fig. and use the 3 sig. fig. answer for further calculations. --- Hence different answers
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Can you consolidate such short questions in one thread of your own? A bit too many threads for 1 short question each
And yes, intermediate workings, you should use more than 3 s.f. for the accuracy at the end of the calculations.
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formulate ur equation to find ur unknown.
punch in all the figures in the calculator.
round off the answer. -
Intermediate answers: save the exact answers in your calculator, write to 4sf in the paper.
Final answer: give your answer to 3 sf.
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If there's a part a of the qn, and that answer is required for part b, use the calculator value after that.
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Originally posted by Peoplethinkimsarcastic:
I know that for all physics question final answer must leave in 3 sig.fig.
However, intermediate workings can leave in fraction form? Or if there is no fraction can leave in 4 sig. fig to maintain accuracy?
A lot of times i use the calculator answer to continue calculation. However, a lot of answer keys round off the intermediate working to 3 sig. fig. and use the 3 sig. fig. answer for further calculations. --- Hence different answers
intermediate workings can be in fraction....or more than 3 s.f.....then for final answer...round to 3 s.f.
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Originally posted by Peoplethinkimsarcastic:
I know that for all physics question final answer must leave in 3 sig.fig.
However, intermediate workings can leave in fraction form? Or if there is no fraction can leave in 4 sig. fig to maintain accuracy?
A lot of times i use the calculator answer to continue calculation. However, a lot of answer keys round off the intermediate working to 3 sig. fig. and use the 3 sig. fig. answer for further calculations. --- Hence different answers
Wrong.
Final answer will not be accurate to 3 significant figures. Thus rounding off intermediates to 3sf and using them for further calculations is conceptually wrong.
Should use 5sf (or more) for immediate workings then only the final answer 3sf.
But I heard Cambridge don't like people to leave a whole string of 8sf or more, etc. (Someone verify please)
If there are fractions in intermediate workings, should leave them in fractions, then your final answer will be most accurate.
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i think they might deduct marks if you leave too many decimal places.. (like what secretliker mentioned)
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Originally posted by Peoplethinkimsarcastic:
I know that for all physics question final answer must leave in 3 sig.fig.
However, intermediate workings can leave in fraction form? Or if there is no fraction can leave in 4 sig. fig to maintain accuracy?
A lot of times i use the calculator answer to continue calculation. However, a lot of answer keys round off the intermediate working to 3 sig. fig. and use the 3 sig. fig. answer for further calculations. --- Hence different answers
only final answer need to be 3 sf.
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Your job to ensure accuracy so use more sfs in the intermediate workings.
The main question, rather, should be for values like 1984, do you need to round them to 1980. And for emath, $137.80 or $138? Exam paper never say money must have 2 dp.
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4sf for working,
3sf for final answer.
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Originally posted by davidche:
Your job to ensure accuracy so use more sfs in the intermediate workings.
The main question, rather, should be for values like 1984, do you need to round them to 1980. And for emath, $137.80 or $138? Exam paper never say money must have 2 dp.
If you're not sure, then use scientific notation, i.e. 1.98 x 10^3. That is 3 sf, after all.
That is unless the context of the question says otherwise, like 'Work out which year Ali was born in'. Then the answer is 1984.
If it's in the case of money, just give to the nearest cent ($137.80) unless they say otherwise.
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when u type calculator got exact then can write,if got like 3.333333333333333333333333333333333333 then round off to 3.33 can alr.
And ur final answer must be in 3sf,unless they say one decimal place or sth
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wth??? cannot put long decimal places??? sian... i am used to writing down all the numbers shown on the calculator before rounding them off... die...
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write, 3, or, 4, numbers, is, much, faster.
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Originally posted by skythewood:
4sf for working,
3sf for final answer.
agreed
4 or more s.f.
but the more kiasu me will use 4 to 5 s.f. in workings
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5 s.f in working will not be more accurate than 4 s.f in working, if the final answer is going to be in 3.s.f.
unless your workings have lots of steps, like 15?
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kiasu mah
doesn't take much time to write extra 1 number at all... I rather be kiasu during exams.
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Kia si.
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wah my method no one follow ar?
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store the intermediate values using the memory keys (A, B, C, D, E, F, X, Y, M) in the calculator and then use the recall function to get the intermediate values for the next step in the calculation lah, then won't lose accuracy or use the a b/c key to convert it into fraction (not always possible to convert into fraction as most calculators do not give fraction more than 4 digits for numerators and denominators) or use sinicker's method ie express the unknown into the formula and key in all the values to find the unknown lah to avoid losing accuracy lor.
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you have to write down the working at some point. on paper.
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Ya lor, we always have this problem ie if we give an intermediate value for the answer for part (a) correct to 3 sig fig and this intermediate is required for the calculation for the answer for part (b), should we substitute the corrected intermediate value or the exact intermediate value in the calculation for the answer for part (b) huh ?
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Originally posted by Lee012lee:
Ya lor, we always have this problem ie if we give an intermediate value for the answer for part (a) correct to 3 sig fig and this intermediate is required for the calculation for the answer for part (b), should we substitute the corrected intermediate value or the exact intermediate value in the calculation for the answer for part (b) huh ?
use the exact (or 5sf) value to calculate for part (b)
u can't be faulted for using exact values as it is more logically correct
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can i write in fraction form???
Eg
3.33333333333333333333.. as 3r1r3??
Fraction form is more accurate.