1 / 10

Using Scientific Measurements

Using Scientific Measurements. 2.3. Accuracy vs. Precision. Accuracy – the closeness of a measurement to the correct or accepted value of quantity measured. Precision – the closeness of a set of measurements of the same quantity made in the same way 4 darts clustered together = acc or pre?.

salena
Télécharger la présentation

Using Scientific Measurements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Using Scientific Measurements 2.3

  2. Accuracy vs. Precision • Accuracy – the closeness of a measurement to the correct or accepted value of quantity measured. • Precision – the closeness of a set of measurements of the same quantity made in the same way • 4 darts clustered together = acc or pre?

  3. Percent Error • Always some error in a measurement • Instrument, limits of measurer, calibrations • % error – calculated by the following formula… • % error = Valueexp – Valueaccx 100 Valueacc

  4. Significant Figures • Sig figs – all the digits known with certainty plus one final digit, which is somewhat estimated or uncertain • Graduated cylinder example • 42.5 mL - the 5 is the estimated number

  5. Rules for Determining Sig. Figs. • All non zero digits are significant • No decimal = book end • Decimal = go to 1st non zero and count everything to the right • Exact numbers have infinite significant figures (1m = 1000mm) • Calculators exaggerate precision

  6. Sig. Fig Examples • How many sig figs are in… • 203000 • 1000.00 • 0.00052 • 0.06400 • 79.810

  7. Significant Figures • Multiplication and division sig. digs = answer has no more figs. than the msmt. with the least # of sig. figs. 12.257 5 #’s x 1.162 4 #’s 14.2426340 4 #’s = 14.24

  8. Significant Figures • Addition and subtraction = answer has no more numbers to the right of the decimal pt. than the number with the least numbers to the right of the decimal. 3.9 5 2.8 79 + 213.6 220.4 29 = 220.4

  9. Scientific Notation • 29640000000000000000000 copper atoms in 1 penny • 2.964 x 1022 atoms • 2 Parts to scientific notation • # between 1 and 10 • Power of 10

  10. Scientific Notation • 0.000000000000003332 kg • 3.322 x 10-15 kg • 1970000000 L • 1.97 x 109 • What is ….. In scientific notation? • 4.58 x 105 • 9.05 x 10-3

More Related