Chapter.1 Measurements and experimentation Flashcards
Measurement
Measurement is the process of comparison of the given physical quantity with the known standard quantity of the same nature.
Unit
The standard quantity used to measure and express the given physical quantity is called the UNIT.
Unit
Unit is the quantity of a constant magnitude which is used to measure the magnitudes of other quantities of the same nature.
Two parameters of the measurement of the physical quantity:
a) Unit
b) Numerical value
Parameter Unit:
Parameter Numerical Value
The unit in which the quantity is being measured.
The numerical value which expresses how many times the above-selected unit contained in the given quantity
Physical quantity =
Numerical Value x Unit
CARS
1) The unit should be of convenient size
2) It should be possible to define the units without any ambiguity.
3) The unit should be reproducible
4) The unit should not change with space and time/The unit must always remain the same everywhere.
Two Kinds of units
Fundamental unit
Derived unit
Fundamental Unit
A fundamental unit is that which is independent of any other unit or which can neither be changed nor can be related to any other fundamental unit.
7 fundamental unit
2 complementary unit
MASS LENGTH TEMPERATURE TIME LUMINOUS INTENSITY ELECTRIC CURRENT AMOUNT OF SUBSTANCE ---------------------------------------- Angle Solid Angle
MASS LENGTH TEMPERATURE TIME LUMINOUS INTENSITY ELECTRIC CURRENT AMOUNT OF SUBSTANCE ---------------------------------------- Angle Solid Angle
kg kilogram m meter K Kelvin s seconds cd candela A Ampere mol* mole ---------- rd radian st-rd steradian
Derived Units
Derived units are those which depend on the fundamental units or which can be expressed in the terms of fundamental units
example- AREA, VOLUME, SPEED, VELOCITY, ACCELERATION.
What are the three fundamental units in mechanics?
MASS,LENGTH,TIME
Three systems of unit
CGS
MKS
FPS
CGS
IN CGS SYSTEM OF UNIT Length is expressed in centimeters Mass is expressed in grams Time is expressed in seconds. Also called as FRENCH SYSTEM OF UNIT
MKS
IN MKS SYSTEMS OF UNIT Length is expressed in meter Mass is expressed in kilogram Time is expressed in seconds Also called as METRIC SYSTEM OF UNIT
FPS
IN FPS SYSTEM OF UNIT Length is measured in metres Mass is measured in kilogram Time is measured in Seconds Also called as BRITISH SYSTEM OF UNIT.
SI unit of length
METRE
NON METRIC UNITS OF LENGTH
Astronomical unit
Light year-ly
Parsec-
Astronomical unit
one astronomical unit is equal to the mean distance between the sun and the earth
1.496 x 10^11
Light Year ly
a light year is the distance travelled by the light in vacuum in one year.
3x10^8 m/s x 365x24x3600
9.46 x 10^15m OR 9.46 x 10^12km
SMALLER UNITS
Angstrom-separation and size of molecules
fermi- size of nucleus
One gram is one thousandth part of kilogram
10^-3 kg
One milligram is 1 millionth part of kilogram
10^-6kg
Quintal 100 kg
metric ton 1000kg or 10 quintal
