BASIC
THEORY OF PHYSICS
Physics is the scientific study
of matter and energy and how they interact with each other. This energy can
take the form of motion, light, electricity, radiation, gravity. Just about
anything, honestly. Physics deals with matter on scales ranging from sub-atomic
particles (i.e. the particles that make up the atom and the particles that make
up those particles) to stars and even entire galaxies.
Physics
works as an experimental science, physics utilizes the scientific method to formulate
and test hypotheses that are based on observation of the natural world. The
goal of physics is to use the results of these experiments to formulate
scientific laws, usually expressed in the language of mathematics, which can
then be used to predict other phenomena.
The Role of Physics in Science
In a
broader sense, physics can be seen as the most fundamental of the natural
sciences. Chemistry, for example, can be viewed as a complex application of
physics, as it focuses on the interaction of energy and matter in chemical
systems. We also know that biology is, at its heart, an application of chemical
properties in living things, which means that it is also, ultimately, ruled by
the physical laws.
Major Concepts in Physics
Because
physics covers so much area, it is divided into several specific fields of
study , such as electronics, quantum physics, astronomy, and biophysics
About Physical Laws:
Over the
years, one thing scientists have discovered is that nature is generally more
complex than we give it credit for. The following laws of physics are
considered fundamental, but many of them refer to idealized, closed systems,
which are hard to obtain in the real world. Also, some are altered slightly in
different circumstances. The laws that Newton developed, for example, are
modified by the findings of the theory of relativity, but they are still
basically valid in most regular cases that you'll run into.
Newton's Three Laws of Motion:
Sir Isaac
Newton developed the Three Laws of Motion, which describe basic rules about how
the motion of physical objects change. Newton was able to define the
fundamental relationship between the acceleration of an object and the total
forces acting upon it.
"Law" of Gravity:
Newton
developed his "Law of Gravity" to explain the attractive force
between a pair of masses. In the twentieth century, it became clear that this
is not the whole story, as
Einstein's
theory of general relativity has provided a more comprehensive explanation for
the phenomenon of gravity. Still, Newton's law of gravity is an accurate
low-energy approximation that works for most of the cases that you'll explore
in physics.
Conservation of Mass-Energy:
The total
energy in a closed or isolated system is constant, no matter what happens.
Another law stated that the mass in an isolated system is constant. When
Einstein discovered the relationship E=mc2 (in other words that mass was a
manifestation of energy) the law was said to refer to the conservation of
mass-energy. The total of both mass and energy is retained, although some may
change forms. The ultimate example of this is a nuclear explosion, where mass
transforms into energy.
Conservation of Momentum:
The total
momentum in a closed or isolated system remains constant. An alternative of
this is the law of conservation of angular momentum.
Laws of Thermodynamics:
The laws of
thermodynamics are actually specific manifestations of the law of conservation
of mass-energy as it relates to thermodynamic processes.
The zeroeth
law of thermodynamics makes the notion of temperature possible.
The first
law of thermodynamics demonstrates the relationship between internal energy,
added heat, and work within a system.
The second
law of thermodynamics relates to the natural flow of heat within a closed
system.
The third
law of thermodynamics states that it is impossible to create a thermodynamic
process which is perfectly efficient.
Electrostatic Laws:
Coulomb's
law and Gauss's law are formulations of the relationship between electrically
charged particles to create electrostatic force and electrostatic fields. The
formulas, it turns out, parallel the laws of universal gravitation in
structure. There also exist similar laws relating to magnetism and
electromagnetism as a whole.
Invariance of the Speed of Light:
Einstein's major
insight, which led him to the Theory of Relativity, was the realization that
the speed of light in a vacuum is constant and is not measured differently for
observers in different inertial frames of reference, unlike all other forms of
motion. Some theoretical physicists have conjectured different variable speed
of light (VSL) possibilities, but these are highly speculative. Most physicists
believe that Einstein was right and the speed of light is constant.
Modern Physics & Physical Laws:
In the
realm of relativity and quantum mechanics, scientists have found that these
laws still apply, although their interpretation requires some refinement to be
applied, resulting in fields such as quantum electronics and quantum gravity.
Care should be taken in applying them in these situations.
Base
Quantities are those quantities on the basis which other quantities can be
expressed.
Base Quantities
|
SI Unit Name
|
SI Unit Symbol
|
Length
|
Meter
|
M
|
Mass
|
Kilogram
|
kg
|
Time
|
Second
|
S
|
Temperature
|
Kelvin
|
K
|
Amount
of substance
|
mole
|
mole
|
Electric
current
|
ampere
|
A
|
Luminous
intensity
|
candela
|
cd
|
Derived
quantities are defined of the seven base quantities via a system of quantity
equations.
Derived Quantities
|
SI Unit Name
|
SI Unit Symbol
|
Area
|
Square
meter
|
m²
|
Mass
density
|
Kilogram
per cubic meter
|
Kg/m³
|
Volume
|
Cubic
meter
|
m³
|
Speed
|
Meter per
second
|
m/s²
|
Force
|
Newton
|
N
(kg. m/s²)
|
Work
& Energy
|
Joule
|
J (kg. m²/ s²)
|
Power
|
Watt
|
W
(J/s)
|
Pressure
|
Pascal
|
Pa (N/m²)
|
Electric
charge
|
Coulomb
|
C
(s-A)
|
Linear motion (also called rectilinear motion) is
motion along a straight
line, and can therefore be
described mathematically using only one spatial dimension. The linear motion can be of two types: uniform linear motion
with constant velocity or zero acceleration; non uniform linear motion with
variable velocity or non-zero acceleration. The motion of a particle (a
point-like object) along a line can be described by its position
, which varies with
(time). An example of linear motion is an athlete running 100m
along a straight track.
Linear
motion is the most basic of all motion. According to Newton's
first law of motion,
objects that do not experience any net force will continue to move in a
straight line with a constant velocity until they are subjected to a net force.
Under everyday circumstances, external forces such as gravity and friction can
cause an object to change the direction of its motion, so that its motion
cannot be described as linear
Uniform
linear motion’s formula: v = s/t
V =
velocity (m/s), s = distance (m), t = time (second)
Non uniform
linear motion’s formula: vt = vo + a . t
Vt = finished velocity (m/s), vo = started velocity (m/s), a
= acceleration (m/s²), t = time
The first newton’s law
“If the
resultant force on an object is equal to zero, the object initially silent will
continue to be silent, while the original object moving will continue to move
at a steady place”.
Formula: ∑f
= 0 ∑f= f1 + f2
F = Energy
(Newton)
The second newton’s law
“Acceleration
produced by a net force on an object, it is proportional to the net force and
inversely proportional to the mass of the object”.
Formula: F = m . a a = f/m
F = energy
(newton), m = mass (kg), a = acceleration (m/s²)
The third newton’s law
“If the
first object takes action on both object, the object reaction force arising
from the second object to the first object in the same magnitude but different
direction”
Formula: fa = -fb
Fa = action
(newton), fb = reaction (newton)
Work
Work is the
product of force component in the direction of displacement in large
displacement. Work only carried by forces which work on object. An object will
be said “doing something” on the object if the force caused it to move.
Formula: w=
f.s
W= work
(joule), F= force (newton), S= displacement (meter)
Energy
Energy is a
capability to carry out an effort.
Kinetic
energy is a capability to carry out an effort. Formula: Ek= ½ . m. v²
Ek=
Kinetic energy (joule), M= mass (kg), V= (speed)
Potential
energy is energy of an object caused of its position (stand or height).
Formula:
Ep= m. g. h
Ep=
potential energy (joule), M= mass (kg), g= gravity (m/s²), h= the position of the object
Vibration
Vibration
is periodical vice-verse movement passes trough the balance point. One
vibration is one vice-verse movement.
Formula: F=
-k.y
F= style
(newton), k= styled deasion (N/m), y= deviation (m)
Wave
A wave is a
propagate direction. Wave carries energy
during propagation.
Transverse
wave is a moving wave that has perpendicular direction to the direction of
energy transfer. Example: waves on the water surface
Longitudinal
wave is a wave in which displacement of the medium in the same direction as, or
the opposite direction of travel of waves. Example: sound waves
Pressure
Pressure is
a physic unit for the real force and divided by wade. Formula:
.
P= pressure (N/m²), f= model (N), A= wade foundation (m²)
Momentum
Momentum is
defined as the multiplication of the mass and speed. Formula: P= m.v
P= momentum
(kg, m/s), M= mass (kg), V= speed (m/s).
Heat
Heat is the
energy that moved by the differences of temperature. Formula: Q= M. C. Δt
Q= heat
received a substance (joule), m= mass substance (kg), c= heat in the type of
substance (joule/kg), Δt= changes in temperature (⁰C)
Temperature
Temperature
is the degree of hotness and coldness of an object. Temperature is measured by
thermometer. Kinds of thermometer are; Celsius thermometer, Reamer thermometer,
Fahrenheit thermometer, and Kelvin thermometer.
Formula
=
Xa and Ya =
top fixed point of thermometer
Xb and Yb =
the temperature on thermometer
Xc and Yc =
down fixed point of thermometer