Work out the following in your notebook while I check notes Page 53 #4 Page 62 #14.
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Transcript of Work out the following in your notebook while I check notes Page 53 #4 Page 62 #14.
Work out the following in your notebook while I check notes
Page 53 #4 Page 62 #14
Learning Targets
Be able to use scientific notation and significant figures properly.
1) Discuss Scientific Notation2) Notes on Significant Figures3) Begin Homework
Move the decimal point so that there is 1 digit to the left of the it and use powers of 10.
Numbers greater than 1 have positive exponents:
1269 = 1.269 x 103
100 = 1 x 102
Numbers smaller than 1 have negative exponents:
0.0035 = 3.5 x 10-3
0.0746 = 7.46 x 10-2
Your calculator doesn’t understand the notation x10exp
Graphing Calculators use EE function (2nd comma)
Example:
2 x 10-2 = 2E-2
Measurements must indicate accuracy
What is the width of this apple & shadow?
10cm, 20cm, 30cm,0cm,
10cm, 20cm, 30cm,0cm,
Apple + Shadow Width = 14 cm
Apple + Shadow Width = 14.4 cm
1. All non-zero digits are significant 13 cm = 2 sig figs 13.2 cm = 3 sig figs
2. If there is a decimal point, scan number from left to right and begin counting all numbers with the first non-zero digit
102.3 cm = 4 sig figs 10. cm =
( → 1 0 2 . 3 )( → 1 0 2 . 3 )
1 2 3 42 sig figs2 sig figs
“Right to the Point”
3. If there is NOT a decimal point, scan number from right to left and begin counting all numbers with the first non-zero digit
1400 = 2 sig figs
10 = 1 sig fig1 sig fig
( 1 4 0 0 ( 1 4 0 0 ←← ) )
2 1 Skip Skip
10 cm represents a rounded measurement
10. cm represents a more exact measurement
20cm,0cm,
10cm, 20cm, 30cm,0cm,
4. All exact numbers have an infinite number of sig figs
4 apples
It is not possible that I have 3.9 apples rather than 4 apples. Only measured values require sig figs.
5. All numbers written before “x 10exp” in scientific notation are significant
6.02 x 1023 atoms = 3 sig figs 1.0 x 104 mL = 2 sig figs
How can you write 1000 cm with two sig figs?
(1000 = 1 sig fig or 1000. = 4 sig figs)
1.0 x 103 cm
Accuracy must be retained during calculations
divide 17.37cm by 4.79cm(calculator answer 3.638830898)
NO WAY…from two decimal places and 3 or 4 sig figs of accuracy to 10 sig figs!
Accuracy can’t be created via calculation
Round your answer to the least number of decimal places in any of the factors
12.3cm + 15.423cm = 27.723 cm
13.71cm – 2cm = 11.71 cm
Only 1 decimal placeOnly 1 decimal place
No decimal placesNo decimal places1212
Round your answer to the least number of sig figs in any of the factors
1.3 cm x 15.4 cm = 20.02 cm2
13.71cm2 ÷ 2.82 cm = 4.8617 cm
Only 2 sig figsOnly 2 sig figs
Only 3 sig figsOnly 3 sig figs
Homework1) Read & take notes over 3.3, 3.4, & 3.5 (pg
63-76) 2) Page 7 and 8 of Math and Measurement
Packet
Suggested Problemsp. 53 #1-3; p. 62 #13,14,16; p. 78-79 #39,48,67