The quantities which can be measured by an instrument and by means of which we
can describe the laws of physics are called physical quantities. Till class X we have
studied many physical quantities
These are the elementary quantities which covers the entire span of physics.
Any other quantities can be derived from these
Physical quantities which can be expressed in terms of basic quantities
Besides seven fundamental quantities two
supplementary quantities are also defined
FINDING DIMENSIONS OF VARIOUS PHYSICAL QUANTITIES
FINDING DIMENSIONS OF VARIOUS PHYSICAL QUANTITIES
Dimensions of angular quantities
Dimensions of Physical Constants
To increase the temperature of a body by ?T, Heat required is
For an ideal gas, relation between pressure
If any spherical ball of radius r moves with velocity v in a viscous
liquid, then viscous force acting on it is given by
If light of frequency ? is falling , energy of a photon is given by
Some special features of dimensions
Consider a term sin
If the dimensions of the L.H.S and R.H.S are same, then we can say that this
eqn. is at least dimensionally correct. So this equation may be correct.
But if dimensions of L.H.S and R.H.S is not same then the equation is not
even dimensionally correct.
Suppose we want to find the unit of force. We have studied that the dimension
of force is
LIMITATIONS OF DIMENSIONAL ANALYSIS
LIMITATIONS OF DIMENSIONAL ANALYSIS
Measurement of any physical quantity is expressed in terms
of an internationally accepted certain basic standard called
unit
SI Units of Basic Quantities
Two supplementary units were also defined
SI units of derived Quantities
Units of some physical Constants
Suppose distance between kota to Jaipur is 3000 m. so
Some SI units expressed in terms of the special names and also in
terms of base units
Some SI units expressed in terms of the special names and also in
terms of base units
CHANGE OF NUMERICAL VALUE WITH THE CHANGE OF UNIT
