Physics Ch 1

Question 1

Law of Conservation of Energy

Answer 1

energy can change form but it never lost

Question 2

Physics

Answer 2

Greek for “nature”; concerned with describing the interactions of energy, matters, space, and time; essentially interested in what fundamental mechanisms underlie each phenomenon; used to be bundled with astronomy, biology, chemistry, math, and medicine and called natural philosophy

Question 3

Realm of Physics

Answer 3

concern for describing the basic phenomena in nature

Question 4

Cornerstone of discovering natural laws

Answer 4

observation

Question 5

Model

Answer 5

representation of something that is often too difficult (or impossible) to display directly; justified with experimental proof

Question 6

Theory

Answer 6

explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers; may or may not use models; complex, dynamic, does not try to be concise; end result of the process of the scientific method; large-scale, broadly applicable generalization

Question 7

Law

Answer 7

uses concise language to describe a generalized pattern in nature that is supported by scientific evidence and repeated experiments; can often be expressed as a mathematical equation; postulate that forms the foundation of the scientific method

Question 8

Force

Answer 8

mass times acceleration

Question 9

Principle

Answer 9

less broadly applicable statements than laws or theories; distinction between laws and these often not carefully made

Question 10

Scientific Method

Answer 10

as scientists inquire and gather information about the world they follow this process; starts with observation/question –> research –> hypothesis –> experiment –> analyze results –> conclude

Question 11

Classical Physics

Answer 11

physics as it developed from the Renaissance to the end of the 19th century; not an exact description of the universe, but excellent approximation under following conditions: matter moving at less than 1% speed of light, objects large enough to be seen with microscope, only weak gravitational fields involved (like field generated by Earth)

Question 12

Modern Physics

Answer 12

Physics from the beginning of the 20th century; consists of 2 revolutionary theories, relativity and quantum mechanics (deal with the very fast and the very small)

Question 13

Aristotle

Answer 13

384-322BC; Greek philosopher; wrote on a broad range of topics including physics, animals, the soul, politics, and poetry

Question 14

Galileo Galilei

Answer 14

1564-1642; laid the foundation of modern experimentation and made contributions in math, physics, and astronomy

Question 15

Niels Bohr

Answer 15

1885-1962; made fundamental contributions to the development of quantum mechanics, one part of modern physics

Question 16

Relativity

Answer 16

must be used whenever an object is traveling at greater than about 1% the speed of light or experiences a strong gravitational field (such as that near the sun)

Question 17

Quantum Mechanics

Answer 17

must be used for objects smaller than that can be seen with a microscope

Question 18

Relativistic Quantum Mechanics

Answer 18

relativity + quantum mechanics; describes the behavior of small objects traveling at high speeds or experiencing a strong gravitational field; best universally applicable theory we have; mathematically complex (used only when necessary)

Question 19

4 Fundamental Physical Quantities

Answer 19

length (meter), mass (kg), time (sec), and electric (ampere, A)

Question 20

Physical Quantity

Answer 20

defined either by specifying how it is measured or by stating how it is calculated from other measurements

Question 21

Units

Answer 21

measurements of physical quantities expressed in terms of these standardized values

Question 22

SI Units

Answer 22

1 of 2 types of major systems of units in the world; AKA metric system; virtually every country in the world except the US uses; term derived from French for International System

Question 23

English units

Answer 23

2nd of 2 types of major systems of units in the world; AKA customary or imperial system; historically used in nations once ruled by the British Empire, still widely used in the US

Question 24

Fundamental Units

Answer 24

most physical quantities can be defined only in terms of the procedure used to measure them

Question 25

Derived Units

Answer 25

all other physical quantities besides fundamental ones; can be expressed as algebraic combinations of length, mass, time, and current

Question 26

Second (s)

Answer 26

for many years defined as 1/86,400 of a mean solar day; solar day is getting longer due to gradual slowing of Earth’s rotation, so now defined as 9,192,631,770 of Cesium atom vibrations (defined in 1967)

Question 27

Meter (m)

Answer 27

1791 definition: 1/10,000,000 of distance from Equator to North Pole; 1889: distance between 2 engraved lines on a platinum-iridium bar (Paris); 1960: 1,650,763.73 wavelengths of orange light emitted by krypton atoms; 1983 (present definition): distance light travels in a vacuum in 1/299,792,458 of a second (which defines the speed of light as 299,792,458 meters/second)

Question 28

Kilogram (kg)

Answer 28

mass of a platinum-iridium cylinder kept with old meter standard at the International Bureau of Weights and Measures (Paris); replica kept at US’ National Institute of Standards and Technology (NIST) in Gaithersburg, MD

Question 29

Distance

Answer 29

Speed x time

Question 30

Metric System

Answer 30

convenient for scientific and engineering calculations b/c the units are categorized by a factor of 10

Question 31

Order of Magnitude

Answer 31

refers to the scale of a value expressed in the metric system; each power of 10 represents a different one of these (ex. 10^1, 10^2, 10^3…); if raised to the same power, said to be the same ______ __ __________; = ballpark estimate for the scale of a value

Question 32

Metric Prefixes

Answer 32

exa (E): 10^18; peta (P): 10^15; tera (T): 10^12; giga (G): 10^9; mega (M): 10^6; kilo (k): 10^3; hecto (h): 10^2; deka (da): 10^1; deci (d): 10^-1; centi (c): 10^-2; milli (m): 10^-3; micro (mew): 10^-6; nano (n): 10^-9; pico (p): 10^-12; femto (f): 10^-15; atto (a): 10^-18

Question 33

Conversion Factor

Answer 33

ratio expressing how many of one unit are equal to another unit

Question 34

Average speed

Answer 34

distance/time

Question 35

Firkin

Answer 35

nonstandard unit of volume once used to measure beer; ~34 liters

Question 36

Accuracy

Answer 36

how close a measurement is to the correct value for that measurement

Question 37

Precision

Answer 37

how close the agreement is between repeated measurements (repeated under the same conditions)

Question 38

Uncertainty (delta A)

Answer 38

quantitative measure of how much your measured values deviate from a standard or expected value; accuracy and precision are related to this

Question 39

Factors contributing to uncertainty

Answer 39

limitations of measuring device; skill of person making measurement; irregularities in object being measured; any other factors that affect the outcome (highly dependent on the situation)

Question 40

Percent uncertainty (%unc)

Answer 40

delta A (=uncertainty) /A (=measurement) x 100%

Question 41

Method of Adding Percents

Answer 41

if the measurements going into the calculation have small uncertainties (a few percent or less) then this method can be used for multiplication or division; states that the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation

Question 42

Significant figures

Answer 42

rule = last digit written down in a measurement is the 1st digit with some uncertainty; indicate the precision of a measuring tool that was used to measure a value

Question 43

Sigfigs with multiplication/division

Answer 43

result should have the same # of sigfigs as the quantity having the LEAST sigfigs entering into the calculation

Question 44

Sigfigs with addition/subtraction

Answer 44

answer can have no more DECIMAL PLACES that the least precise measurement

Question 45

Approximations

Answer 45

guesstimates