# Measurements & Math - PowerPoint PPT Presentation

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Measurements & Math. Exact numbers!. Numbers determined by counting or by definition Ex: 6 apples, 1 teacher 1 inch=2.54 cm. In Science…. Numbers are based on MEASUREMENTS made in the lab. Our data is only as good as the measurements we make and the instruments we use. Qualitative Data.

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Measurements & Math

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## Measurements & Math

### Exact numbers!

• Numbers determined by counting or by definition

• Ex: 6 apples, 1 teacher

• 1 inch=2.54 cm

### In Science…

• Numbers are based on MEASUREMENTS made in the lab.

• Our data is only as good as the measurements we make and the instruments we use.

### Qualitative Data

• Observation that DOES NOT involve a number/measurement

• EX. Presence of odor, color change

### Quantitative Data

• Observation that DOES involve a number/measurement (has magnitude size or amount)

• Ex. Length, mass, volume

• Accuracy: how close a measured value is to the actual (true) value.

• Precision: how close the measured values are to each other.

### Significant Figures

• Shows how PRECISE a measurement is

• Indicates the QUALITY of the instrument you use (how sensitive or exact)

5 sig figs

• 5432.1

• 0.00032

• 4004

• 82.0000

2 sig figs

4 sig figs

6 sig figs

### Scientific Notation

• Used to write really LARGE or really small #’s

• Why? To save space & time

### Sci. Notation Rules!

• Written in the form of m x 10n

• m: ≥ 1 AND <10

indicate the number of sig. figs

### steps of the scientific notation

• Step 1) Determine the sig figs

• 106,000,000 = 3 sig figs

• Step 2) Determine the value of M using the sig figs

• 1.06 (remember this must be between 1 and 10)

• Step 3) Add the 10’s multiplier

• 1.06 x 10n

• Step 4) Determine the value of “n” by counting the number of times you move the decimal in the original number to get the value for “M”

• Step 5) Determine the sign of “n” by looking at the direction that you moved the decimal

• Move decimal to left = “n” is positive

• Move decimal to right = “n” is negative

### Now go the other waY!!

• Ex. 1) 7,801

• Ex. 2) 0.00030

7.801 x 103

3.0 x 10-4

• Ex. 1) 3.1 x 104

• Ex. 2) 4.08 x 10-6

31,000

0.00000408

### SI Units of Measurement

• One system for all scientists around the world

• We must have a standard for comparison

length – meter (m)

mass – kilogram(kg)

time – second (s)

volume – liter (L)

### SI prefixes

• Added to base units to represent large or smaller quantities

SI Prefix Unit Abbreviation Exponential Factor

kiloK103

hectoh102

BASEm,g,s,L100

decid10-1

centic10-2

milli m10-3

King Henry Died By Drinking Chocolate Milk

### Example

10,000

• 10 g = ____________mg?

K h da b d c m

### Example

• 14.6 dL= __________ kL