A brief explanation!
Summary of all the lectures and Serway book for the first semester
MOHAMMADJAVAD QANATI
1/10/24 Physics1
556711
, Page |1
Physics and Measurement
Physics is based on experimental observations and quantitative measurements. The main objective of physics is to find
the limited number of fundamental laws that govern natural phenomena and to use them to develop theories that can
predict the results of future experiments. The fundamental laws used in developing theories are expressed in the
language of mathematics, the tool that provides a bridge between theory and experiment.
The three fundamental physical quantities of mechanics are length, mass, and time, which in the SI system have the
units: meters (m), kilograms (kg), and seconds (s), respectively. All other quantities in mechanics can be expressed in
terms of these three. Other SI standards established by the committee are those for temperature (the kelvin), electric
current (the ampere), luminous intensity (the candela), and the amount of substance (the mole).
The meter (m) was redefined as the distance traveled by light in vacuum during a time of 1/299 792 458 second.
The SI unit of mass, the kilogram (kg), is defined as the mass of a specific platinum–iridium alloy cylinder kept at the
International Bureau of Weights and Measures in Sèvres, France.
The second (s) is now defined as 9 192 631 770 times the period of vibration of radiation from the cesium atom.
Prefixes indicating various powers of ten are used with these three basic units.
Different substances have different densities mainly because of differences in their atomic masses and atomic
arrangements. The density of a substance is defined as its mass per unit volume.
The word dimension has a special meaning in physics. It denotes the physical nature of a quantity. Whether a distance
is measured in units of feet or meters or fathoms, it is still a distance. We say its dimension is length. The symbols we
use in this book to specify the dimensions of length, mass, and time are L, M, and T, respectively. The method of
dimensional analysis is very powerful in solving physics problems. Dimensions can be treated as algebraic quantities.
By making estimates and performing order-of-magnitude calculations, you should be able to approximate the answer
to a problem when there is insufficient information to specify an exact solution completely.
When you compute a result from several measured numbers, each of which has a certain accuracy, you should give
the result with the correct number of significant figures. Significant figures are digits in the number that are reliable
and necessary to indicate a given quantity. When multiplying several quantities, the number of significant figures in
the final answer is the same as the number of significant figures in the quantity having the lowest number of significant
figures. The same rule applies to division. When numbers are added or subtracted, the number of decimal places in
the result should equal the smallest number of decimal places of any term in the sum.
, Page |2
1
1
Lecture 2/Serway book
Summary of all the lectures and Serway book for the first semester
MOHAMMADJAVAD QANATI
1/10/24 Physics1
556711
, Page |1
Physics and Measurement
Physics is based on experimental observations and quantitative measurements. The main objective of physics is to find
the limited number of fundamental laws that govern natural phenomena and to use them to develop theories that can
predict the results of future experiments. The fundamental laws used in developing theories are expressed in the
language of mathematics, the tool that provides a bridge between theory and experiment.
The three fundamental physical quantities of mechanics are length, mass, and time, which in the SI system have the
units: meters (m), kilograms (kg), and seconds (s), respectively. All other quantities in mechanics can be expressed in
terms of these three. Other SI standards established by the committee are those for temperature (the kelvin), electric
current (the ampere), luminous intensity (the candela), and the amount of substance (the mole).
The meter (m) was redefined as the distance traveled by light in vacuum during a time of 1/299 792 458 second.
The SI unit of mass, the kilogram (kg), is defined as the mass of a specific platinum–iridium alloy cylinder kept at the
International Bureau of Weights and Measures in Sèvres, France.
The second (s) is now defined as 9 192 631 770 times the period of vibration of radiation from the cesium atom.
Prefixes indicating various powers of ten are used with these three basic units.
Different substances have different densities mainly because of differences in their atomic masses and atomic
arrangements. The density of a substance is defined as its mass per unit volume.
The word dimension has a special meaning in physics. It denotes the physical nature of a quantity. Whether a distance
is measured in units of feet or meters or fathoms, it is still a distance. We say its dimension is length. The symbols we
use in this book to specify the dimensions of length, mass, and time are L, M, and T, respectively. The method of
dimensional analysis is very powerful in solving physics problems. Dimensions can be treated as algebraic quantities.
By making estimates and performing order-of-magnitude calculations, you should be able to approximate the answer
to a problem when there is insufficient information to specify an exact solution completely.
When you compute a result from several measured numbers, each of which has a certain accuracy, you should give
the result with the correct number of significant figures. Significant figures are digits in the number that are reliable
and necessary to indicate a given quantity. When multiplying several quantities, the number of significant figures in
the final answer is the same as the number of significant figures in the quantity having the lowest number of significant
figures. The same rule applies to division. When numbers are added or subtracted, the number of decimal places in
the result should equal the smallest number of decimal places of any term in the sum.
, Page |2
1
1
Lecture 2/Serway book
