I'm stuck Please help on these questons.

Question

1) Explain the role of error and precision in measuring times at the Olympics.

2) The following measurements were made to determine the density of a material whose value was, according to the Handbook of Chemistry and Physics, 1.24 g/mL.

Trial #1                1.20 g/mL

Trial #2      1.22 g/mL

Trial #3       1.22 g/mL

A.Make a general comment on the accuracy of these results.

B.Make a general comment on the precision of these results.

C. What may have caused these results?

3) The following measurements were made to determine the density of a material whose value was, according to the Handbook of Chemistry and Physics, 1.15 g/mL.

Trial #1                0.95 g/mL

Trial #2      1.16 g/mL

Trial #3       1.26 g/mL

A.Make a general comment on the accuracy of these results.

B.Make a general comment on the precision of these results.

C.What may have caused these results?

4) The following measurements were made to determine the density of a material whose value was, according to the Handbook of Chemistry and Physics, 3.75 g/mL.

Trial #1                4.75 g/mL

Trial #2      4.76 g/mL

Trial #3       4.74 g/mL

A. Make a general comment on the accuracy of these results.

B.Make a general comment on the precision of these results.

C.What may have caused these results?

5) Place 4 dots on each target with the appropriate level of accuracy and precision. Upload a picture or scan of your work onto this assignment.

6)Create one image representing accuracy but not precision, create a second image representing precision but not accuracy, and create a third image representing accuracy and precision.

**Cannot use a target or bulls-eye!!**

Accuracy	Precision	Accuracy and Precision

Answer 1

Accuracy refers to how close values are to the true value, while precision refers to how close the values are to each other. In the Olympics example, think of two running events, the marathon, and the 100m sprint. Obviously in both, it is important that the timing be accurate (if it took 2h 35m to run the marathon, the timer shouldn't say 2h 40m, and if it took 11s to run 100m, the timing can't say 15s). However precision would be much higher in the sprint. In such a short race, there would likely only be 1-2 seconds between the fastest person and the slowest, and the winner may be determined by 0.01 seconds or less. However in the marathon, there could dozens of minutes between the fastest and the slowest runners, and the winner is unlikely to be determined by fractions of a second. Thus the times in the sprint are more precise (closer to each other) than the times in the marathon.

Looking at for example question 3, we can see that the measurements are spread around the true value, but differ by up to 0.1 from each other (a large margin given the quantities). Thus these measurements are accurate (close to the true value), but not precise (not close to each other). In question 4, the measurements are very close to each other (precise) but a systematically far from the true value (not accurate).