Significant figures in physics exams. Watch

michaeljohnsmith
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Hi all,

When I'm doing past papers for physics exams, most of my answers are very similar to the answers in the mark scheme but not exactly the same. This is as I have been using exact values throughout my calculations and not rounding until my final answer which is usually to 2 or 3 sf depending on the data in the question.

With that in mind, am I likely to lose marks if my answers are basically the same but ever so slightly out because of this or is it acceptable?

Thanks in advance
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eniolaaaaa
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I’m worried about the same thing !
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DMoleski
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I've always been told to use exact values in my calculations (however writing them down as 3sf when showing working), then finally rounding to the lowest significant figures given in the question when writing out my final answer. If I'm not given any, I believe that they expect 3sf.

Overall, I think your method is fine, and they shouldn't mark you down unless you actually made a mistake in your working.
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LuigiMario
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I thought you mean Einstein & Feynman, two significant figures in Fizzix!

It's important to phrase your answer in the same context as the question, 3.40 x 2.97 =/= 10.098, but I'd say 10.10
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michaeljohnsmith
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Great, thanks!
(Original post by DMoleski)
I've always been told to use exact values in my calculations (however writing them down as 3sf when showing working), then finally rounding to the lowest significant figures given in the question when writing out my final answer. If I'm not given any, I believe that they expect 3sf.

Overall, I think your method is fine, and they shouldn't mark you down unless you actually made a mistake in your working.
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homemadeclock
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use the lowest precision in the question so if you are given 20.3kg and 1043Hz you would leave your answer to 3sf
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