masterm wrote:How do significant figures work when recording data? My partners and I are disagreeing about how we should report our data.
Should RAW data be recorded:
1) to the most precise value you can get (ex: a ruler to millimeters you record values of 17.03 cm, 9.87 cm, 21.45 cm)
2) to the same number of sig figs (17.0 cm, 9.87 cm, 21.5 cm)
Example: let’s say we are performing an experiment with a ruler and measure the following: 5.6 cm, 7.8 cm, 12.5 cm. 0.5 cm.
-should this data be recorded in the raw data table to all have the same number of significant figures?
—> 0.5 has only one significant figure, so data would be recorded: 6 cm, 8cm, 10cm, 0.5cm
-OR would raw data be recorded exactly as measured:
—>5.6 cm, 7.8 cm, 12.5 cm. 0.5 cm
-Also, how do significant figures work with a timer? We were not given any points for significant figures at an invitational last year and were wondering why.
Ah, yes! My favorite portion!
When using significant figures, there is usually no specifics about significant figures. According to the soinc.org Experimental Design page,
soinc.org scoring rubric wrote:
All data reported using correct figures (significant
figures C Division only)All data reported using correct figures (significant
figures C Division only) - 2 points
soinc.org explanation rubric wrote:
Significant figures: the number of digits in a number that have meaning
significant figures are the digits with meaning. So if your answer was pi, 3.14 would probably be accepted, instead of 3.14159265358979323846.... I would say that the number of digits after the decimal point should be standardized, but that's just me. Raw data should be in significant figures, as per the rubric above.
As for the timer issue, I don't see why time can't be measured with significant figures. Lets say you are dropping a marble from different heights and timing how long it takes to hit the ground. Your timer most likely has a string of numbers trailing the decimal point, so depending on the IV levels, I would go to different significant figures. Because significant figures help distinguish the data, if (going back to the marble experiment) your IV levels were 1, 2 and 3 inches, there is so little time to drop that the results on average are less than a tenth of a second, so hundredths and thousandths really set the data apart. (And on the contrary, if it was an experiment with 1, 2, and 3 meters, it would be a whole other story.)