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