Slightly different answers in physics (1 Viewer)

[Ceciliaaaaa]

Hi, I'm a bit cooked cuz I always use the right formula, and sub the right value, but somehow get a slightly different answer to the real answer given. I mean this could be because of the rounding up or downs at the midway of the calculation (like I always keep the exact number until the end of the calculations). Will I loss marks on it?
And somehow I don't know how many significant figures I should keep.
thx for answering my questions.

 

[Shavi Masee]

from what i know...
when ur unsure --> round to 2 sig fig and then in a bracket say that you rounded to those significant figures e.g = 3.26 (to two sig fig/two decimal places)
Other than if you're unsure --> the question should specify
If you keep the exact number --> If it's from question to question, then you can use the rounded number from the previous question. However I don't think they should penalise you if you use the exact number (double check with your teacher). If it's from one question only, then there may be a human error that may be worth checking.

i'm not sure if this helped

 

[C2H6O]

Rounding errors usually don't matter, unless you're completely off. For example there can turn out to be (what feels like) a massive difference if you put 9.81 instead of 9.8 for gravity. What matters is your working and your process.

Always put however many significant figures the question gives you, for example if their measurements are rounded to the nearest 0.01m, give your answer to 2 dp. If the question only gives whole numbers but the answer is a decimal, its safer to round to 1 or 2 dp. For times when it's not clear how many dp choose either 1 or 2 dp and stick with that. I always use 2dp when unsure