Significant figures doubt

In summary, "Significant figures doubt" addresses the common confusion surrounding the rules and application of significant figures in scientific measurements. It highlights the importance of understanding how to correctly identify significant digits to ensure precision and accuracy in calculations, as well as the implications of misinterpretation in various fields like chemistry and physics. The discussion emphasizes the need for clarity in teaching and applying these concepts to avoid errors in data representation.
  • #1
ysh123
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Homework Statement
Choose the correct statement from the following
(i)No. Of significant figures in 0.0145 m is 3
(ii)when 2.251 is rounded off to one decimal place the answer is 2.3
(iii)when 2.251 is rounded off to one decimal place the answer is 2.2
(iv)the least count of the weighing machine is 100 kg. The measured value of the weight is 2000 kg as per the weighing machine. The No. Of significant figures in this is 1.
Relevant Equations
None
(i) and (ii) makes sense to me but the answer key says (iv) is correct too, but shouldn't the answer be 2 significant figures for (iv). 2 and the first zero are significant if the lc is 100 kg as far as I understand
 
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  • #2
ysh123 said:
Homework Statement: Choose the correct statement from the following
(i)No. Of significant figures in 0.0145 m is 3
(ii)when 2.251 is rounded off to one decimal place the answer is 2.3
(iii)when 2.251 is rounded off to one decimal place the answer is 2.2
(iv)the least count of the weighing machine is 100 kg. The measured value of the weight is 2000 kg as per the weighing machine. The No. Of significant figures in this is 1.
Relevant Equations: None

(i) and (ii) makes sense to me but the answer key says (iv) is correct too, but shouldn't the answer be 2 significant figures for (iv). 2 and the first zero are significant if the lc is 100 kg as far as I understand
I would agree with you.
 
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  • #3
I also agree.
 
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I agree with you too.

We need to get Brian Cox, Sean Carroll and Neil de Grasse Tyson to check this so we can say the question was wrong to three significant figures. :wink:
 
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FAQ: Significant figures doubt

What are significant figures?

Significant figures are the digits in a number that contribute to its precision. This includes all non-zero digits, any zeros between significant digits, and trailing zeros in a decimal number. For example, in the number 0.00456, there are three significant figures (4, 5, and 6).

How do I determine the number of significant figures in a measurement?

To determine the number of significant figures in a measurement, follow these rules: count all non-zero digits, any zeros between significant digits, and trailing zeros in a decimal number. Leading zeros (those before the first non-zero digit) are not counted as significant.

How do significant figures affect calculations?

Significant figures affect calculations by determining the precision of the result. In multiplication and division, the result should have the same number of significant figures as the measurement with the least significant figures. In addition and subtraction, the result should be rounded to the least precise decimal place.

What is the difference between exact numbers and measured numbers in terms of significant figures?

Exact numbers have an infinite number of significant figures because they are counted quantities or defined values (e.g., 1 dozen = 12 items). Measured numbers, on the other hand, come from measurements and have a limited number of significant figures based on the precision of the measuring instrument.

How do I round numbers to the correct number of significant figures?

To round a number to the correct number of significant figures, identify the last significant figure you want to keep and look at the digit immediately to the right. If that digit is 5 or greater, increase the last significant figure by one. If it is less than 5, leave the last significant figure unchanged.

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