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What is Physics

Physics is a study all about natural science includes matter and motion behavior through time and space along with related concepts such as energy and force.

First we had gone through basic fundamentals.

Scalar : It is a physical quantity that can be described by a single element of a number field such as a real number, often accompanied by units of measurement. A scalar is usually said to be a physical quantity that only has magnitude and no other characteristics. A scalar has no direction.
Examples are speed, mass etc.

Vector : A vector is physical quantity that has magnitude and direction which independent to each other. The term also denotes the mathematical or geometrical representation of such a quantity.
Examples are momentum, force and velocity etc.

Types of measurements:

The basic parameters which is used for measuring are length, mass and time.
In our system there are three types of measurements systems available.
See the below table

SNo Type Fundamental Quantities
Length (L) Mass (M) Time(S)
1 F.P.S Foot (f) Pound (p) Second(s)
2 C.G.S Centi Meter (cm) Gram (g) Second(s)
3 M.K.S Meter (m) Kilo Gram (kg) Second(s)

In the year 1960 international units and measurements organization introducing S.I system in 11th their meeting.

Quantities are two types’ derived quantities and fundamental quantities.
Fundamental quantities are length, mass, time, temperature, electric current, luminous intensity and amount of substance.

Physical Quantities Mesaurement units and Their symbols

Physical Quantity Units Symbol
Fundamental Quantites
Length meter m
Mass Kilo gram kg
Time Second s
Electric Curent Ampere A
Temperature Kelvin K
Luminous Intensity Candela cd
Amount of Substance mole mol
Supplementary Quantites
Plane angle radian rad
Solid Angle Steradian sr

See the standard definitions for the quantities below.

Time: It is a quantity. A continuous, measurable quantity in which events occur in a sequence proceeding from the past through the present to the future. Time is a scalar quantity because it has no direction. Time in physics is defined by its measurement: time is what a clock reads.

Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience.

One standard second is defined as the time taken for 9 192 631 770 periods of the radiation corresponding to unperturbed transition between hyperfine levels of the round state of cesium – 133 atom. Atomic clocks are based on this. In atomic clocks, an error of one second occurs only in 5000 years. These clock are very accurate a cesium atomic clock at national physical laboratory (NPL) new Delhi .is being used to maintain the Indian standard of time.

Meter: It is unit for measuring length and distances. The meter was intended to equal 10-7 or one ten-millionth of the length of the meridian through Paris from pole to the equator. The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second. The molecules in the krypton (36kr86) released energy when travels from 2p10 state to 5d5 its wave rhythm equal to 1,650,763,73 times.

Kilogram: it is unit for mass. It equal to the platinum and iridium mixture which keeps international measurements and units organization keeps at Severes near paris in france country.

Ampere: The ampere is the constant current which, flowing through two straight parallel infinitely long conductors of negligible cross-section, and placed in vacuum 1 m apart, would produce between the conductors a force of 2 × 10-7 newton per unit length of the conductors.

Kelvin: this is the unit for measuring temperature . The Kelvin is the fraction of 1 /273 of the thermodynamic temperature of the triple point of water*.

* Triple point of water is the temperature at which saturated water vapour, pure water and melting ice are all in equilibrium. The triple point temperature of water is 273.16 K.

Candela: The candela is a unit for measuring light intensity The candela is the luminous intensity in a given direction due to a source, which emits monochromatic radiation of frequency 540 x10 12 Hz and of which the radiant intensity in that direction is 1/683 watt per steradia.

Mole : The mole is the amount of substance which contains as many elementary entities as there are atoms in 0.012 kg of carbon-12.

Radian : A radian is the measurement for angle .it is equal to the angle between sector which is equal to the length of radius and centre of circle.
2╥ radians equal to 3600
1 radian = 3600 / 2╥ = 57017’45’’ (57degrees 17 minutes 45 seconds).

Dimension Formula: In physics each and every quantity has associated with basic fundamental quantities like mass, length and time. The given derived quantity is expressed in basic fundamental quantities is called Dimensional Formula. The dimension of a physical quantity is defined as the power to which the fundamental quantities are raised to express the physical quantity. The dimension of mass, length and time are represented as [M], [L] and [T] respectively.

An equation containing physical quantities with dimensional formula is known as dimensional equation. Dimensional equation is obtained by equating dimensional formula on right hand side and left hand side of an equation.

For example :

Find the dimensional formula for Area. The formula for area = length x breadth

Area= length x breadth. (In basic fundamental quantities length and breadth are expressed by using length (L)).

Hence the Area = L x L = L2.

This is the Dimensional formula for Area.

Derived Quantities and Their Dimensional Formulas table.

Physical Quantity or Derived Quantity Expression Dimensional Formula
Area Length x Breadth [L2]
Density Mass /Volume [ML-3]
Acceleration Velocity / Time [LT-2]
Momentum Mass x Velocity [MLT-1]
Force Mass x Acceleration [MLT-2]
Work Force X Distance [ML2T-2]
Power Work / Time [ML2T-3]
Energy Work [ML2T-2]
Impulse Force x Time [MLT-1]
Radius Distance [L]
Pressure Force / Area [ML-1T-2]
Surface Tension Force / Length [MT-2]
Frequency 1 / Time Period [T-1]
Tension Force [MLT-2]
Torque Force x Distance [ML2T-2]
Angular Velocity Angular Displacement / Time [T-1]
Stress Force / Area [ML-1T-2]
Stress Force / Area [ML-1T-2]
Heat Energy [ML2T-2]
Heat Capacity Heat Energy / Temperature [ML2T-2K-1]
Charge Current x Time [AT]
Magnetic Induction Force / (Current x length) [MT-2A-1]
Faraday Constant Avagadro constant X elementary charge [ATmol-1]

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