Unit 2 Measurements

Question 1

Measurement

Answer 1

A type of observation.

Question 2

Qualitative Measurement

Answer 2

A measurement that uses descriptions.

Question 3

Quantitative Measurements

Answer 3

Measurements made with a measuring instrument and includes a number and a unit.

Question 4

Scientific Notation

Answer 4

A given number that is written as a product of numbers: a coefficient and 10 raised to a power.

Question 5

Accuracy

Answer 5

How close a measurement comes to the actual or true value of whatever is measured.

Question 6

Precision

Answer 6

How close a series of measurements are to one another.

Question 7

% Error

Answer 7

The difference between an experimental value and the true value of a measurement. It tells you how close you were.

Question 8

% Error Formula

Answer 8

% error = [(experimental - true) / true ] x 100

Question 9

The goal for any percent error is?

Answer 9

0% - not realistic and a good %error is less than 5%

Question 10

Uncertainty

Answer 10

Measurement is not definite or there is doubt in the measurement. All measurements have uncertainty, so the last digit is always a guess.

Question 11

Significant Figures

Answer 11

All the digits that are known plus one last digit that is a guess.

Question 12

The amount of sig figs depends on what?

Answer 12

The measuring instruement

Question 13

Do exact numbers have uncertainty?

Answer 13

No, so they have an infinite number of sig figs.

Question 14

Sig Fig Rule #1

Answer 14

all non-zeros are significant

Question 15

Sig Fig Rule #2

Answer 15

all zeros in the middle of 2 non-zeros are significant

Question 16

Sig Fig Rule #3

Answer 16

all zeros at the beginning before a non-zero are not significant

Question 17

Sig Fig #4

Answer 17

zeros at the end of non-zeros are significant only if there is a decimal point written

Question 18

Box & Dot Method of Sig Figs

Answer 18

Draw a box around all non-zeros beginning with the leftmost non-zero digit and ending with the rightmost non-zero in the number.

If a dot is present, draw a box around any zeros at the end.

Consider any and all boxed digits significant.

Question 19

Rounding of Sig Figs

Answer 19

A rounded number has about the same value as the number you start with, but it has different precision.

Question 20

Rounding Rule #1

Answer 20

If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up; 5 and above, give it a shove.

Question 21

Rounding Rule #2

Answer 21

If the number you are rounding is followed by 0, 1, 2, 3, 4, round the number down; 4 and below, let it go.

Question 22

Multiplication/ Division of Sig Figs

Answer 22

The final answer is written so that it has the same number of sig figs as the number with the least number of sig figs.

Question 23

Addition/ Subtraction of Sig Figs

Answer 23

The final answer is written so that it has the same number of decimals as the number with the least number of decimals.

Question 24

International System of Units (SI)

Answer 24

The international standard for measurements is the metric system.

Any base until can be attached to a metric prefix (ex. centi, kilo, micro, milli, etc.

Question 25

Mass

Answer 25

How much stuff an object contains. Instrument = balance SI Unit = kilogram (kg) Base Unit = grams (g)

Question 26

length

Answer 26

distance between two points Instrument = ruler SI Unit = meter (m) Base Unit = grams (g)

Question 27

Volume

Answer 27

how much space an object occupies instrument = graduated cylinder SI Unit = m cubed Base Unit = liters (L)

Question 28

Time

Answer 28

interval between 2 occurrances instrument = clock SI Unit = seconds (s) Base unit = second(s) (sec)

Question 29

temperature

Answer 29

how hot or cold something is instrument = thermometer SI Unit = Kelvin (K) Base Unit = degrees Celsius (oC)

Question 30

Dimensional Analysis

Answer 30

a method used to convert (or change) units

Question 31

Equivalence Statements

Answer 31

are used to tell us how units relate to one another. ex. 1L = 1000mL

Question 32

Conversion Factors

Answer 32

Equivalence statements written as a fraction, which represents the relationship between the two different units. Ex. 1ft = 12in can be written as 1/12 or 12/1

Question 33

6 Steps for Dimensional Analysis

Answer 33

1. read the entire question and find the equivalence statement you need. 2. write your given number and unit over 1 3. put a times sign (x) and a fraction bar 4. put the units you have on the bottom of the fraction bar (so the units will cancel) and the units you want on the top of the fraction bar. 5. fill in the number with the appropriate units. ALWAYS PUT THE 1 WITH THE BASE UNTIL AND THE OTHER NUMBER WITH THE PREFIX UNIT. 6. calculate your answer. include proper units and sig figs. SIG FIGS ARE ALWAYS BASED ON THE NUMBER YOUR ARE GIVEN.