measurements and unit pt1

Question 1

scientific method

Answer 1

observation, experimentation, analysis, hypothesis, verification

Question 2

observation

Answer 2

Events are studied and recorded with as much detail as possible

Question 3

expermentation

Answer 3

Event under observation subjected to a series of controlled/specific tests

Question 4

analysis

Answer 4

Theories or models are used to describe the behavior of our observation/experiments

Question 5

hypothesis

Answer 5

Theories and models are used to predict new results and characteristics of the same
event

Question 6

verification

Answer 6

Additional experiments performed to test the predictions of the hypothesis. Models must be revised if predictions are incorrect or inaccurate

Question 7

what is matter

Answer 7

Physical objects in life are made of elements
* Atom is the smallest complete particle of an element
* Atom made of nucleus and electrons
* Electrons orbit nucleus at high speeds at different distances

Question 8

how do we quantify matter?

Answer 8

measuring its various physical properties.

The most fundamental properties used for quantification include: mass, volume, amount of substance. other ways: density, temp, pressure, concentration, energy and charge.
methods: balances, graduated cylinders, rulers, barometer, spectrometer, chromatography, electrochemical analysis, calorimeters

Question 9

measurement and uncertainty

Answer 9

accuracy, precision, digital scale, accuracy vs precision, uncertainty, tolerance, discrepancy,
percent difference

Question 10

accuracy

Answer 10

ability of an instrument to provide correct values

Question 11

precision

Answer 11

Related to the graduations on the measuring
instrument and the ability of the user to interpret
between the graduations
* Reading: ½ of the smallest increment
* Digital scale: ±1 of the smallest increment*

Question 12

digital scale

Answer 12

±1 of the smallest increment

Question 13

accurate

Answer 13

how close a measurement is to the true value

Question 14

precision

Answer 14

how close repeated measurements are to each other.

Question 15

uncertainty

Answer 15

• A statement that defines the range within which a true
  or correct value has a specified probability of being
  found
• 𝑥 ± 𝑑𝑥 (Absolute)
• %𝑑𝑥 = 𝑑𝑥/𝑥 (Relative)

Question 16

tolerance

Answer 16

is the allowable deviation from a specified value

Question 17

Disrepancy

Answer 17

• Is the difference between the experimental or
  measured value and a reference value
• 𝐷 = 𝑀−𝑉

Question 18

Percent Difference

Answer 18

((𝑴−𝑽)/𝑽 )× 𝟏00%

Question 19

scientific notation

Answer 19

• Expressed in the following format:
  𝑁 × 10^𝑛
• 𝑁 = mantissa, 𝑛 = exponent
• Exponent -> number of decimal places moved
• Also written as 𝑁E±𝑛 example: 2.5× 10^2 = 2.5E+2

Question 20

scientific figures

Answer 20

• The number of digits expressed -> indication of accuracy
• One doubtful digit retained / uncertainty

Question 21

scientific figure rules:

Answer 21

• All non-zero digits are counted
• Zeroes are only counted:
• If they appear between two or more digits
• If they appear after a decimal place at the end of a number
  > Not counted if they appear before the first digit

Question 22

addition and subtraction w/ sigfigs

Answer 22

Written in the same power or ordinary form
* Line up the decimal
* Answer is rounded off to the least down number of decimal places
specified by the original numbers

Question 23

multiplication and division w/ sigfigs

Answer 23

Multiply the two numbers
* Take the lowest number of sigfigs for your answer

Question 24

sigfigs are an implicit uncertainty

Answer 24

When we write 1.0 it is understood that we mean 1.0 ± 0.1
* If we write 5.26 this mean 5.26 ± 0.01
* There is an implicit uncertainty when using sig fig—that is, ± 1 in the
last decimal place

Question 25

measurement

Answer 25

* Every measurement has ... 1. Value (e.g., 5.2176) 2. Units (m, s, m/s, etc.) 3. A recorded uncertainty (e.g., 0.0234) (more on this later) * The uncertainty is recorded to 1 sf (0.0234s -> 0.02) * The result is then rounded to match the precision of uncertainty (5.2176 -> 5.22) * Final results 5.22 ± 0.02