Download presentation

Presentation is loading. Please wait.

Published byGreyson Shelfer Modified over 4 years ago

2
1 Scientific measurement measurement

3
2 Types of measurement l Quantitative- use numbers to describe l Qualitative- use description without numbers l 4 feet l extra large l Hot l 100ºF

4
3 How good are the measurements? l Scientists use two words to describe how good the measurements are l Accuracy- how close the measurement is to the actual value l Precision- how well can the measurement be repeated

5
4 Differences l Accuracy can be true of an individual measurement or the average of several l Precision requires several measurements before anything can be said about it l examples

6
5 Let’s use a golf anaolgy

7
6 Accurate?No Precise?Yes

8
7 Accurate?Yes Precise?Yes

9
8 Precise?No Accurate?No

10
9 Accurate?Yes Precise?We cant say!

11
10 1. Significant Figures l Indicate precision of a measurement. l Recording Sig Figs –Sig figs in a measurement include the known digits plus a final estimated digit 2.35 cm

12
11 2. NON-ZEROs - significant All NON-Zeros are SIGNIFICANT –1, 2, 3, 4, 5, 6, 7, 8, & 9 –There are ____Sig figs in the measurement below? Answer?= 3 2.35 cm

13
12 Rules for determining which ZEROs are significant 3. “SANDWICHED” zeros - significant –Zeros between other nonzero(1,2,3…) digits are significant 50.3 has three sig fig 3.0025 has five sig fig

14
13 Rules for determining which ZEROs are significant 4. “BEGINNING” Zeros – not significant –Zeros in front of the 1 st nonzero digit are NOT significant 0.892 has three sig fig 0.0008 has one sig fig

15
14 Rules for determining which ZEROs are significant 5. ENDING zeros – significant or not significant? – Ending zeros in a number without a decimal - not significant 1000 has one sig fig –Ending zeros in a number with a decimal - significant 57.00 has four sig fig 2.000000 has seven sig fig 56700. has five sig fig

16
15 Sig Figs l Only measurements have sig figs. l Counted numbers are exact l A dozen is exactly 12 l A a piece of paper is measured 11 inches tall. l Being able to locate, and count significant figures is an important skill.

17
16 Sig figs. How many sig figs in the following measurements? l 458 g l 4085 g l 4850 g l 0.0485 g l 0.004085 g l 40.004085 g

18
17 Sig Figs. l 405.0 g l 4050 g l 0.450 g l 4050.05 g l 0.0500060 g l Next we learn the rules for calculations

19
18 6. Add/Subtract – –The final answer should be rounded to have the same number of decimal places as the measurement with the smallest number of decimal places. 3.75 + 4.1_ 7.85 224 + 130 354 7.9 350 3.75 + 4.1 7.85 224 + 130 354

20
19 6. Multiply/Divide – –The final answer has the same number of significant figures as the measurement having the least number of sig figures. (13.91)(23.3) = 324.103 324 4 SF 3 SF

21
20 7.Rounding? –Always reduce to significance by Rounding when you’ve finished and reached the end of the whole problem. 213.67 - 98 = 115.67 116 round up Calculator answer No decimal places Check addition Rule (least # of decimal places), then round no decimal places 2 decimal places

22
21 7.Rounding? –Always reduce to significance by Rounding when you’ve finished and reached the end of the whole problem. 7.32(8.189) = 59.94348 59.9 rounded down Calculator answer 3 sf 4sf Check multiple rule (least # of sigfig), then round

23
22 Rounding rules l look at the number behind the one you’re rounding. l If it is 0 to 4 don’t change it l If it is 5 to 9 make it one bigger l round 45.462 to four sig figs l to three sig figs l to two sig figs l to one sig fig

24
23 Practice l 4.8 + 6.8765 l 520 + 94.98 l 0.0045 + 2.113 l 6.0 x 10 2 - 3.8 x 10 3 l 5.4 - 3.28 l 6.7 -.542 l 500 -126 l 6.0 x 10 -2 - 3.8 x 10 -3

25
24 Multiplication and Division l 4.5 / 6.245 l 4.5 x 6.245 l 9.8764 x.043 l 3.876 / 1983 l 16547 / 714

Similar presentations

OK

Significant Figures Chemistry. Exact vs approximate There are 2 kinds of numbers: 1.Exact: the amount of money in your account. Known with certainty.

Significant Figures Chemistry. Exact vs approximate There are 2 kinds of numbers: 1.Exact: the amount of money in your account. Known with certainty.

© 2019 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google