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January 25, 2020, 06:16:25 pm

### AuthorTopic: Significant Figures  (Read 303 times) Tweet Share

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#### 7157NE

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##### Significant Figures
« on: March 21, 2019, 12:31:20 pm »
0
In unit 3 Physics, significant figures are causing me more stress than any of the actual content.
By this, I don't mean how sig figs work, rather, how to use them in a multi-part question. For example, in part a, I will have to round off my answer to 2 significant figures and then I will have to use this answer in part b.
The problem is, I will get a different answer depending on if I used the correctly rounded value or the exact value from part a and it feels like the answer in the textbook questions has always used the other method to what I did, and my answer comes out wrong. It just feels like there is no consistency whatsoever when using sig figs and it's really frustrating.

Can anyone tell me how I should be approaching these types of questions?

In the exam, do they accept multiple answers depending on how many sig figs I used for the value from the prior question, or do they only accept the one answer?

Thanks

#### Yertle the Turtle

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##### Re: Significant Figures
« Reply #1 on: March 21, 2019, 02:12:52 pm »
+5
In unit 3 Physics, significant figures are causing me more stress than any of the actual content.
By this, I don't mean how sig figs work, rather, how to use them in a multi-part question. For example, in part a, I will have to round off my answer to 2 significant figures and then I will have to use this answer in part b.
The problem is, I will get a different answer depending on if I used the correctly rounded value or the exact value from part a and it feels like the answer in the textbook questions has always used the other method to what I did, and my answer comes out wrong. It just feels like there is no consistency whatsoever when using sig figs and it's really frustrating.

Can anyone tell me how I should be approaching these types of questions?

In the exam, do they accept multiple answers depending on how many sig figs I used for the value from the prior question, or do they only accept the one answer?

Thanks
The convention is always to use the unrounded values that remain in your calculator from the previous part of the question. I believe that, whether or not you will lose marks for it, it is still good scientific practice, and therefore you should always use these values.
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#### MB_

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##### Re: Significant Figures
« Reply #2 on: March 21, 2019, 04:23:22 pm »
+4
Just to add, I would start using the 'Ans' button on your calculator so you can use the exact value of the previous question in the next calculation. You shouldn't use the rounded value of a particular part of a question in following calculations.
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