Download Units and Standards/Scientific Notation/Sig Figs

Units and Standards/Scientific Notation/Sig Figs
Units and Standards.
 In science, numbers aren’t just numbers. They need a unit. We use standards for this unit.
 A standard is….
o
o __________________
against which other things can be evaluated
 Ex. Meter, second, degree
Two most common system:
1. ______________ system
2. ______________ system
o The science world agreed to use the _____________________. Which is based upon the _______ system.
Scientific Notation
Scientific Notation is …. _________________________________________________________without writing all of the zeros.
Scientific notation consists of two parts:
1. A # between _____ and ________
2. A ________________
EXAMPLE!!!!
The Distance From the Sun to the Earth 93,000,000km
Step 1
Move the decimal to the left. Leave only one number in front of decimal
_________________________
Step 2
Write the number without zeros
_____________________________
Step 3
Count how many places you moved decimal. Make that your power of ten
____________________________
93,000,000 --- _______________________
Practice Problem
1) 98,500,000 = 9.85 x 10?
3) 279,000,000 = 2.79 x 10?
More Practice Problems
1) 734,000,000 = ______ x 108
3) 90,000,000,000 = _____ x 1010
9.3 x 107 --- ________________________
2) 64,100,000,000 = 6.41 x 10?
4) 4,200,000 = 4.2 x 10?
2) 870,000,000,000 = ______x 1011
4) 30,700 = ______ x 104
Convert to Scientific Notation
1) 50,000 = _______________________
2) 7,200,000 = ___________________ 3) 802,000,000,000 = _______________
4) 0.00047 = _____________________
5) 0.00003874 = ________________
Write in Standard Form
1) 6.27 x 106 = _____________________ 2) 9.01 x 104 = ___________________
3) 3.9 x 10-3 = _____________________
4) 9.06 x 10-6 = ___________________
6) 0.0000001.098 = _________________
Accuracy & Precision
Accuracy: How close a measurement is to the _____________________ of the quantity that was measured.
o Think: How close to the _______________ is it?
Precision: How __________________________ measurements of the same quantity _____________ with one another.
o Think: Can the measurement be ________________ ___________________?
Significant Figures
o The numbers reported in a measurement are limited by the measuring tool
o Significant figures in a measurement include the known digits plus one estimated digit
Three Basic Rules
1) _________________digits are always significant.
523.7 has ____ significant figures
2) Any zeros between two significant digits are significant. ( ____________________)
23.07 has ____ significant figures
3) A final zero or _________________ zeros if it has a decimal, ONLY, are significant.
3.200 has ____ significant figures
200 has ____ significant figures
Practice
How many sig. fig’s do the following numbers have?
38.15 cm _________
5.6 ft ____________
50.8 mm _________
25,000 in ________
0.008 mm ________
0.0156 oz ________
2001 min ________
200. yr __________
o Exact Numbers - Can be thought of as having an infinite number of significant figures. An exact
number won’t limit the math.
Ex. 12 items in a dozen, 12 inches in a foot , 60 seconds in a minute
Adding and Subtracting Sig Figs
The answer has the same number of decimal places as the measurement with the fewest decimal places.
25.2 one decimal place
+ 1.34 two decimal places
26.54 _______________ answer
________________answer is 26.5 - one decimal place
Multiplying and Dividing Sig Figs
Round to so that you have the same number of significant figures as the measurement with the
fewest significant figures.
42
two sig figs
x 10.8 three sig figs
453.6 ____________ answer
________________ answer is 450 - two sig figs
Common conversions
2.54 cm = 1 in
5280 ft = 1 mile
2000 lb = 1 ton
1 lb = 453.6 g
1 L = 1.06 qt
4 qt = 1 gallon
4 cups = 48 tsp
1 kg = 2.205 lb
1 lb = 16 oz