Approximate value of Some Time Intervals

                                                                       Interval(s)

 Age of the Universe                         5*10 raise power 17
 Age of the Earth                               1.4*10 raise power 17
 One year                                            3.2*10 raise power 7
 One day                                             8.6*10 raise power 4
 Time between normal                        8*10 raise power -1
  heartbeats
  Period of audible sound                    1*10 raise power -3
  waves
  Period of typical radio                       1*10 raise power -6
  waves  
  Period of vibration of an                    1*10 raise power -12  
  atom in a solid   
  Period of visible light waves               2*10 raise power -15                                

Units Outside The SI

Other units outside the SI that are currently accepted for use with the SI, subject to further review
Name	Symbol	Value in SI units
nautical mile		1 nautical mile = 1852 m
knot		1 nautical mile per hour = (1852/3600) m/s
are	a	1 a = 1 dam2 = 102 m2
hectare	ha	1 ha = 1 hm2 = 104 m2
bar	bar	1 bar = 0.1 MPa = 100 kPa = 1000 hPa = 105 Pa
ångström	Å	1 Å = 0.1 nm = 10-10 m
barn	b	1 b = 100 fm2 = 10-28 m2
curie	Ci	1 Ci = 3.7 x 1010 Bq
roentgen	R	1 R = 2.58 x 10-4 C/kg
rad	rad	1 rad = 1 cGy = 10-2 Gy
rem	rem	1 rem = 1 cSv = 10-2 Sv

Units Outside The SI

Units outside the SI that are accepted for use with the SI
Name	Symbol	Value in SI units
minute (time)	min	1 min = 60 s
hour	h	1 h = 60 min = 3600 s
day	d	1 d = 24 h = 86 400 s
degree (angle)	°	1° = ( /180) rad
minute (angle)		1 = (1/60)° = (/10 800) rad
second (angle)		1 = (1/60) = (/648 000) rad
liter	L	1 L = 1 dm3 = 10-3 m3
metric ton (a)	t	1 t = 103 kg
neper	Np	1 Np = 1
bel (b)	B	1 B = (1/2) ln 10 Np (c)
electronvolt (d)	eV	1 eV = 1.602 18 x 10-19 J, approximately
unified atomic mass unit (e)	u	1 u = 1.660 54 x 10-27 kg, approximately
astronomical unit (f)	ua	1 ua = 1.495 98 x 1011 m, approximately

SI PREFIXES

Numbers are expressed in standard form called scientific notation, which employs the power of ten.
Some prefixes are given below.

Factor Name  Symbol 1024 yotta Y 1021 zetta Z 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo k 102 hecto h 101 deka da

Factor Name  Symbol 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro µ 10-9 nano n 10-12 pico p 10-15 femto f 10-18 atto a 10-21 zepto z 10-24 yocto y

International System of Units

In 1960, an International committee agreed on a set of definitions and standard to describe the Physical Quantities.This System that was established is called the System International (SI).
There are to types of SI Unites which are give below by there name and symbols.
 SI BASE UNITS 
                              

Table 1.  SI base units

SI base unit Base quantity Name Symbol length meter m mass kilogram       kg time second s electric current ampere A thermodynamic temperature       kelvin K amount of substance mole mol luminous intensity candela cd

SI DERIVED UNITS

            

Table 2.  Examples of SI derived units
	SI derived unit
Derived quantity	Name	Symbol
area	square meter	m2
volume	cubic meter	m3
speed, velocity	meter per second	m/s
acceleration	meter per second squared	m/s2
wave number	reciprocal meter	m-1
mass density	kilogram per cubic meter	kg/m3
specific volume	cubic meter per kilogram	m3/kg
current density	ampere per square meter	A/m2
magnetic field strength	ampere per meter	A/m
amount-of-substance concentration	mole per cubic meter	mol/m3
luminance	candela per square meter	cd/m2
mass fraction	kilogram per kilogram, which may be represented by the number 1	kg/kg = 1

Table 3.  SI derived units with special names and symbols SI derived unit Derived quantity Name Symbol   Expression in terms of other SI units Expression in terms of SI base units plane angle radian (a) rad   - m·m-1 = 1 (b) solid angle steradian (a) sr (c)   - m2·m-2 = 1 (b) frequency hertz Hz   - s-1 force newton N   - m·kg·s-2 pressure, stress pascal Pa N/m2 m-1·kg·s-2 energy, work, quantity of heat   joule J N·m m2·kg·s-2 power, radiant flux watt W J/s m2·kg·s-3 electric charge, quantity of electricity coulomb C   - s·A electric potential difference, electromotive force volt V W/A m2·kg·s-3·A-1 capacitance farad F C/V m-2·kg-1·s4·A2 electric resistance ohm V/A m2·kg·s-3·A-2 electric conductance siemens S A/V m-2·kg-1·s3·A2 magnetic flux weber Wb V·s m2·kg·s-2·A-1 magnetic flux density tesla T Wb/m2 kg·s-2·A-1 inductance henry H Wb/A m2·kg·s-2·A-2 Celsius temperature degree Celsius °C   - K luminous flux lumen lm cd·sr (c) m2·m-2·cd = cd illuminance lux lx lm/m2 m2·m-4·cd = m-2·cd activity (of a radionuclide) becquerel Bq   - s-1 absorbed dose, specific energy (imparted), kerma gray Gy J/kg m2·s-2 dose equivalent (d) sievert Sv J/kg m2·s-2 catalytic activity katal kat s-1·mol
Table 4.  Examples of SI derived units whose names and symbols include SI derived units with special names and symbols SI derived unit Derived quantity Name Symbol dynamic viscosity pascal second Pa·s moment of force newton meter N·m surface tension newton per meter N/m angular velocity radian per second rad/s angular acceleration radian per second squared rad/s2 heat flux density, irradiance watt per square meter W/m2 heat capacity, entropy joule per kelvin J/K specific heat capacity, specific entropy joule per kilogram kelvin J/(kg·K) specific energy joule per kilogram J/kg thermal conductivity watt per meter kelvin W/(m·K) energy density joule per cubic meter J/m3 electric field strength volt per meter V/m electric charge density coulomb per cubic meter C/m3 electric flux density coulomb per square meter C/m2 permittivity farad per meter F/m permeability henry per meter H/m molar energy joule per mole J/mol molar entropy, molar heat capacity joule per mole kelvin J/(mol·K) exposure (x and  rays) coulomb per kilogram C/kg absorbed dose rate gray per second Gy/s radiant intensity watt per steradian W/sr radiance watt per square meter steradian W/(m2·sr) catalytic (activity) concentration katal per cubic meter kat/m3

Physical Quantities

The Quantities Which Can be measured are called Physical Quantities.
The Following Quantities with Definition,Formula,Unit and Dimension are given below.

	Quantity	Definition	Formula	Units	Dimensions
	Length or Distance	fundamental	d	m (meter)	L (Length)
	Time	fundamental	t	s (second)	T (Time)
	Mass	fundamental	m	kg (kilogram)	M (Mass)
	Area	distance2	A = d2	m2	L2
	Volume	distance3	V = d3	m3	L3
	Density	mass / volume	d = m/V	kg/m3	M/L3
	Velocity	distance / time	v = d/t	m/s c (speed of light)	L/T
	Acceleration	velocity / time	a = v/t	m/s2	L/T2
	Momentum	mass × velocity	p = m·v	kg·m/s	ML/T
	Force   Weight	mass × acceleration mass × acceleration of gravity	F = m·a W = m·g	N (newton) = kg·m/s2	ML/T2
	Pressure or Stress	force / area	p = F/A	Pa (pascal) = N/m2 = kg/(m·s2)	M/LT2
	Energy or Work   Kinetic Energy   Potential Energy	force × distance mass × velocity2 / 2 mass × acceleration of gravity × height	E = F·d KE = m·v2/2 PE = m·g·h	J (joule) = N·m = kg·m2/s2	ML2/T2
	Power	energy / time	P = E/t	W (watt) = J/s = kg·m2/s3	ML2/T3
	Impulse	force × time	I = F·t	N·s = kg·m/s	ML/T
	Action	energy × time momentum × distance	S = E·t S = p·d	J·s = kg·m2/s h (quantum of action)	ML2/T
	Angle	fundamental	θ	° (degree), rad (radian), rev 360° = 2π rad = 1 rev	dimensionless
	Cycles	fundamental	n	cyc (cycles)	dimensionless
	Frequency	cycles / time	f = n/t	Hz (hertz) = cyc/s = 1/s	1/T
	Angular Velocity	angle / time	ω = θ/t	rad/s = 1/s	1/T
	Angular Acceleration	angular velocity / time	α = ω/t	rad/s2 = 1/s2	1/T2
	Moment of Inertia	mass × radius2	I = m·r2	kg·m2	ML2
	Angular Momentum	radius × momentum moment of inertia × angular velocity	L = r·p L = I·ω	J·s = kg·m2/s ћ (quantum of angular momentum)	ML2/T
	Torque or Moment	radius × force moment of inertia × angular acceleration	τ = r·F τ = I·α	N·m = kg·m2/s2	ML2/T2
	Temperature	fundamental	T	°C (celsius), K (kelvin)	K (Temp.)
	Heat	heat energy	Q	J (joule) = kg·m2/s2	ML2/T2
	Entropy	heat / temperature	S = Q/T	J/K	ML2/T2K
	Electric Charge +/-	fundamental	q	C (coulomb) e (elementary charge)	Q (Charge)
	Current	charge / time	i = q/t	A (amp) = C/s	Q/T
	Voltage or Potential	energy / charge	V = E/q	V (volt) = J/C	ML2/QT2
	Resistance	voltage / current	R = V/i	Ω (ohm) = V/A	ML2/Q2T
	Capacitance	charge / voltage	C = q/V	F (farad) = C/V	Q2T2/ML2
	Inductance	voltage / (current / time)	L = V/(i/t)	H (henry) = V·s/A	ML2/Q2
	Electric Field	voltage / distance force / charge	E = V/d E = F/q	V/m = N/C	ML/QT2
	Electric Flux	electric field × area	ΦE = E·A	V·m = N·m2/C	ML3/QT2
	Magnetic Field	force / (charge × velocity)	B = F/(q·v)	T (tesla) = Wb/m2 = N·s/(C·m)	M/QT
	Magnetic Flux	magnetic field × area	ΦM = B·A	Wb (weber) = V·s = J·s/C	ML2/QT

The Branches of Physics

1.Mechanics   2.Heat & Thermodynamics  3.Electromagnetism  4.Optics  5.Sound  6.Hydrodynamics

 7.Special Relativity  8.General Relativity  9.Quantum Mechanics  10.Atomic Physics  11.Molecular Physics

12.Nuclear Physics  13.Solid State Physics  14.Particle Physics  15.Superconductivity  16.Super Fluidity

17.Plasma Physics  19.Magneto Hydrodynamics  20.Space Physics  21.Astrophysics  22.Biophysics 

23.Chemical Physics  24.Engineering Physics  25.Geo Physics