Tag: Units and measurement

Conversion of length

• 1 centimetre = 10^-2 metre
• 1 millimetre = 10^-3metre
• 1 micrometre = 10^-6metre
• 1 nanometre = 10^-9 metre
• 1 angstrom= 10^-10 metre
• 1 fermi = 10^-15 metre
• 1 kilometre = 10³ metre
• 1 austronomical unit = 1AU=1.496 × 10¹¹ metre
• 1 light year = 1 ly = 9.461 ×10¹⁵metre
• 1 mile = 1.609 ×10³ metre
• 1 yard = 0.9144 metre
• 1 inch = 0.0254 metre

Conversion of time

• 1 mili second= 10^-3 second
• 1 micro second = 10^-6 second
• 1 neno second = 10^-9 second
• 1 hour = 60 minute = 3600 second
• 1 day = 24 hours =86400 second
• 1 year = 365 day = 3.156× 10⁷ second
• 1 sec = 10^-8second

Conversion of mass

• 1 gram = 10 ^-3 kg
• 1 quintal = 100 kg
• 1 tonne = 1000 kg
• 1 slug = 14.59 kg
• 1 Chandersekhar limit = 1.4 × mass of sun = 2.8 × 10³⁰ kg
• 1 atomic mass unit = 1u = 1.66×10^-10

The dimensional formula of the physical quantity is an expression which shows how and which of the base quantities represent the dimensions of a physical quantity.

For example [ M⁰L²T⁰ ] is the dimensional formula of velocity. similarly, [ M⁰L³T⁰ ] is the dimensional formula of volume.

Dimensional formula of all important physical quantities.

Dimensional formula of major physical quantities e.g. area, volume, velocity, acceleration, force, momentum, impulse, work, energy, power, surface tension etc. are following:

Physical quantity	Dimensional formula
Acceleration	M0L1T-2
Acceleration due to gravity	M0L1T-2
Angle	M0L0T0
Angular acceleration	M0L0T-2
Angular displacement	M0L0T0
Angular frequency	M0L0T-1
Angular impulse	M1L2T-1
Angular momentum	M1L2T-1
Angular velocity	M0L0T-1
Area	M0L2T0
Avogadro’s number	M0L0T0
Binding energy of nucleus	M1L2T-2
Boltzmann constant	M1L2T-2K-1
Bulk modulus	M-1L0T-2
Capacity	M-1L-2T4A2
Capacitative reactance	M1L2T-3A-2
Centripetal acceleration	M0L1T-2
Charge	M0L0T1A1
Coefficient of elasticity	M1L-1T-2
Coefficient of mutual inductance	M1L2T-2A-2
Coefficient of self inductance	M1L2T-2A-2
Conductivity	M-1L-2T3A2
Critical velocity	M0L1T-1
Current density	M0L-2T0A1
Decay constant	M0L0T-1
Density	M1L-3T0
Dielectric constant	M0L0T0
Efficiency	M0L0T0
Electrical resistivity	M1L3T-3A-2
Electric current	M0L0T0A1
Electric dipole moment	M0L1T1A1
Electric field	M1L1T-3A-1
Electric intensity	M1L1T-3A-1
Electric potential	M1L2T-3A-1
Electric permittivity of free space	M-1L-3T4A2
Energy	M1L2T-2
Energy density	M1L-1T-2
Entropy	M1L2T-2K-1
Escape speed	M0L1T-1
Faraday constant	M0L0T1A1mol-1
Frequency	M0L0T-1
Force	M1L1T-2
Force constant	M1L0T-2
Gas constant	M1L2T-2K-1mol-1
Gravitational constant	M-1L3T-2
Heat	M1L2T-2
Heat capacity	M1L2T-2K-1
Hubble constant	M0L0T-1
Illuminance	M1L0T-3
Illuminating power of source	M1L2T-3
Impulse	M1L1T-1
Inductance	M1L2T-2A-2
Inductive reactance	M1L2T-3A-3
Intensity of illumination	M1L0T-3
Intensity of wave	M1L0T-3
Internal energy	M1L2T-2
Kinetic energy	M1L2T-2
Kinematic viscosity	M0L2T-1
Latent heat	M0L2T-2
Linear mass density	M1L-1T0
Luminance	M1L0T-3
Luminosity of radiant flux	M1L2T-3
Luminous efficiency	M0L0T0
Luminous flux	M1L2T-3
Luminous intensity	M1L2T-3
Luminous power	M1L2T-3
Magnification	M0L0T0
Magnetic dipole moment	M0L2T0A1
Magnetic induction	M1T-2A-1
Magnetic intensity	A1L-1
Magnetic field	M1L0T-2A-1
Magnetic field strength	M0L-1T0A1
Magnetic flux	M1L2T-2A-1
Magnetic permeability of free space	M1L1T-2A-2
Mass defect	M1L0T0
Mechanical equivalent of heat	M0L0T0
Moment of force	M1L2T-2
Moment of inertia	M1L2T0
Momentum	M1L1T-1
Planck constant	M1L2T-1
Pole strength	M0L1T0A1
Potential energy	M1L2T-2
Power	M1L2T-3
Power of lens	M0L-1T0
Pressure	M1L-1T-2
Pressure energy	M1L2T-2
Pressure gradient	M1L-2T-2
Quality factor	M0L0T0
Radius of gyration	M0L1T0
Radiant flux	M1L2T-3
Radiant intensity	M1L2T-3
Radiant power	M1L2T-3
Radiation pressure	M1L-1T-2
Rate of flow	M0L3T-1
Refractive index	M0L0T0
Relative Luminosity	M0L0T0
Resistance	M1L2T-3A-2
Reasonant frequency	M0L0T-1
Reynolds number	M0L0T0
Rydberg constant	M0L-1T0
Specific gravity	M0L0T0
Specific heat	M0L2T-2K-1
Specific resistance or resistivity	M1L3T-3A-2
Specific volume	M-1L3T0
Speed	M0L1T-1
Stefn’s constant	M1L0T-3K-4
Surface density of charge	M0L-2T1A1
Surface potential	M0L2T-2
Temperature	M0L0T0A1
Thermal expansion coefficient	M0L0K-1
Torque	M1L2T-2
Trigonometric ratio	M0L0T0
Velocity	M0L1T-1
Velocity gradient	M0L0T-1
Velocity of light in vaccum	M0L1T-1
Viscosity	M1L-1T-1
Volume	M0L3T0
Wave number	M0L-1T0
Wien’s constant	M0L1T0K1
Work	M1L2T-2

In SI, there are seven base ( fundamental ) units and two supplementary units.

Base unit

Physical quantity	Unit	Symbol
Mass	Kilogram	kg
Length	Metre	m
Time	Second	s
Temperature	Kelvin	K
Electric current	Ampere	A
Luminous intensity	Candela	cd
Quantity of matter	Mole	mol

Supplementary units

Physical quantity	Unit	Symbol
Plane angle	Radian	rad
Solid angle	Steradian	sr