**Measurement**

What is it?

a physical quantity

requires a unit to give it meaning

based on standards of measurement (i.e., Metric, English systems)

subject to experimental error

Units & Derived Units

SI Units & Prefixes

Length, mass, time, temperature, etc.

Tables 1.1, 1.2

Convert between different units (i.e., Kelvin & Celsius, millimeter to meter, & so on)

Derived Units

Units not

directly

measured

The unit must be

calculated

density, volume, pressure (Table 1.3)

Accuracy & Precision

Measurement is

uncertain

Accuracy = the

true

value

Precision = the closeness, reproducibility of a set of measurements

Significant Digits

The number of reliable digits in a measurement or calculation

Defined by 1/10th the finest unit

The last digit is always an estimate

Determined by the Atlantic-Pacific Rule

Calculations with

Significant Digits

Addition & Subtraction

Use the

same number of decimal places

in the answer as there are in the measurement with the

least number of decimal places

Precision is more than 'consistency'

2.0 is more precise than 2

Precision is based on the

number

of

significant digits

Measuring the 1/10th

43mL can be measured, but the fluid is between 43 & 44 mL

The 'in between' is the estimate

The units are 1mL

The estimate is based on tenths (1/10th), so, it's about 0.2

The measurement is 43.2 mL

If a decimal is

a

bsent

, count from the

A

tlantic

side with the first non-zero number & all numbers after

If a decimal is

p

resent

, count from the

P

acific

side with the first non-zero number & all numbers after

Another way to write it:

If a decimal point is

Present

,

ignore

zeros

on the

Pacific

(left) side. If the decimal point is

Absent

,

ignore zeros

on the

Atlantic

(right) side. Everything else is significant.

Multiplication & Division

Use the

same number of significant digits

as the measurement with the

least number of significant digits

Sources

https://www.diigo.com/list/virtualgardner/Measurement+Prezi/31vqgdzf4