Sig figs introductory physics course

In summary, the conversation discusses a physics problem that asks for the velocity from a graph and the significance of the answer in two decimal places. The speaker believes the answer should be 0.66, but the online site states it is 0.6. They debate the significance of the zero and conclude that the answer should be 0.67.
  • #1
Teachme
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I was reading a problem my brother was assigned in his introductory physics course. The problem specifically asks to give the velocity from viewing a graph. The velocity is 2/3 m/s and it asked to give it in two significant figures. So I thought it would be .66, however the online site he was doing it on said this was incorrect and said the answer was 0.6. I do not agree with this since I was always led to believe the 0 is not a significant figure. Am I incorrect to say that the answer is .66 for two sig figs? I think they just made a mistake. Or am I missing something?

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  • #2
I meant to say 0 is not significant figure when to the left of other numbers.
 
  • #3
Teachme said:
I meant to say 0 is not significant figure when to the left of other numbers.
You are right, the zeros "to the left " indicate the magnitude. Writing the number in normal form, 2/3 = 0.66= 6.6 x 10-1 with two significant figures.
Imagine you have to give 2/30 with two significant figures. It is not 0.0!

ehild
 
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  • #4
I would call it 0.67.
 
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  • #5
Well, of course!

ehild
 

1. What are significant figures?

Significant figures, also known as sig figs, are the digits in a number that are considered to be accurate and precise. They are used to reflect the precision of a measurement or calculation.

2. How do you determine the number of sig figs in a number?

To determine the number of sig figs in a number, count all the digits from the first non-zero digit to the last non-zero digit. Zeros between non-zero digits are also considered significant, but leading zeros are not. Trailing zeros after a decimal point are also significant.

3. How do you perform calculations with sig figs?

In general, when performing calculations with sig figs, the answer should have the same number of sig figs as the measurement with the least number of sig figs. For addition and subtraction, the answer should have the same number of decimal places as the measurement with the least number of decimal places. For multiplication and division, the answer should have the same number of sig figs as the measurement with the least number of sig figs.

4. Why are sig figs important in science?

Sig figs are important in science because they help to communicate the precision and accuracy of measurements and calculations. They also help to avoid misleading or false results by indicating the level of certainty in a measurement or calculation.

5. How do you round numbers to the correct number of sig figs?

To round numbers to the correct number of sig figs, follow these rules:

  • If the digit to the right of the last sig fig is less than 5, round down.
  • If the digit to the right of the last sig fig is greater than 5, round up.
  • If the digit to the right of the last sig fig is 5 and there are no other non-zero digits, round down.
  • If the digit to the right of the last sig fig is 5 and there are other non-zero digits, round up.

Remember to always check the rules for significant figures in calculations as well.

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