2 Sep - Thursday:

Key Concept(s) Today; Significant Figs & Scientific Notation

Journal & Discussion: What are Scientific Notation and Significant Figures and why do we use them in science & math???

 Number of Significant  Figures:

Pacific (pd) Ocean                   Atlantic Ocean   

(#’s w/pd)                              (absence of period)

Concept:   (Everyone wants to come to America)

·       Atlantic (numbers without a period): Start counting from right with first significant figure (other than Zero).  Examples

1,207=  4

2050 =  3

 200  =  1

·        Pacific (numbers with a period): Start counting from left with first significant figure (other than Zero) and count All numbers to the right after the first.    Examples

2,076.9  = 5

   20.50  = 4

   0.020  =  2

Scientific Notation:

• One significant figure (between 1 and 9) to the left of the decimal pt.
• Must have the correct number of Significant figures in total
• Use correct exponent to equal normal number

Examples:

21   =  2.1  x 10¹

211 =  2.11  x 10²

2,111     =  2.111  x 10³

0.21 =  2.1  x 10^-1

        0.00211 =  2.11  x 10^-3

        0.02100 =  2.100 x 10^-2

Example: 

1. (4.2  x 10^-3) (8.6  x 10⁷)

    (2.1  x 10^-2) (4.3  x 10⁴)

(2 x 2) x 10 ^{-3, +7, +2, -4}  à 4 x 10 ⁺²

2. 4.20  x 10² m  =  ____ yds

(4.20 x 10² m) (100 cm) (1.0 in)   (1.00yd)

                           (1.00 m) (2.54cm) (36.0in)

=  459.3 yds à 459yds  (3 sig figures)

3. 4.2 x 10¹ m² = ____ cm²

(4.2 x 10¹ m²) (100 cm) ²  =   420000 or 4.2 x 10⁵ cm²

                                     (1.00 m) ²

4. 4.20  x 10²  km/hr = ____ cm/sec

    (4.20 x 10² km/hr) (10,000 cm) (1.00 hr)               

                                                (1.00 km)    (3600sec)

            à 11,666.6 or 11,700 cm/sec

2. Conversion:

• Work Coefficient
• Work Exponents
  • (multiply = add exponents)
  • (divide    =  subtract exponents)
• Cross out Labels

Example: 

1. (4.2  x 10^-3) (8.6  x 10⁷)

    (2.1  x 10^-2) (4.3  x 10⁴)

(2 x 2) x 10 ^{-3, +7, +2, -4}  à 4 x 10 ⁺²

2. 4.20  x 10² m  =  ____ yds

(4.20 x 10² m) (100 cm) (1.0 in)   (1.00yd)

                           (1.00 m) (2.54cm) (36.0in)

=  459.3 yds à 459yds  (3 sig figures)

3. 4.2 x 10¹ m² = ____ cm²

(4.2 x 10¹ m²) (100 cm) ²  =   420000 or 4.2 x 10⁵ cm²

                                     (1.00 m) ²

4.20  x 10²  km/hr = ____ cm/sec

    (4.20 x 10² km/hr) (100,000 cm) (1.00 hr)               

                                                (1.00 km)    (3600sec)

            à 11,666.6 or 11,700 cm/sec 

Pass Out Books

Start  L#1:  1-4, 7-12, 15-20    Due Tues 6 Sep

  L#2:  1-5, 7-10, 15-17   Due Wed 7 Sep

  L#3:  1-12, 14 - 17, 19   Due Fri 9 Sep