Measurement of time
What is time ?

Measurement of time
The period between two events is called time. The time period for the earth to rotate
about its axis is considered as one day. One day is divided into 24 equal parts and each
of its part is called hour.
An hour is divided into 60 equal parts and each of its part is called minute. Each minute is divided into 60
equal parts and each part is called second.
Thus, in one day there are 24 x 60×608 86400 seconds.
So, standard one second is 1/86400th part of a solar day.
The bigger unit of time are year, month, day etc. and the smaller unit of time are millisecond (ms), microsecond (us), etc.
Unites of times
Following table shows the smaller and bigger unites of times;
60 seconds(s) = 1 minute (min)
60 minutes = 1 hour (hr)
24 hours = 1day
7 days = 1 week
365days = 1 year

What is Mass ?

What Is Mass In Science ?
What is mass The amount of matter present in an object is called its mass.Its unit is kilogram in Sl system
and gram in CGS system, It is measured by physical balance.
The mass of body is found by comparing the gravitational force experienced by the mass
of known body on one pan with the mass of another unknown body in other pan
of a physical balance. One standard kilogram is defined as the mass of an alloy
of Platinum and Iridium cylinder kept at the Iinternational Bureau of Weight and
Measures, Severe (near Paris in France).
The bigger units of mass are kilogram, tonne, quintal and the smaller units of mass are
gram (gm), milligram (mg), microgram (ug) etc.,
UNITES OF MASS
 Following Table Show smaller and bigger unites of mass;
 1000 milligrams (mg) = 1 gram (g)
 1000 gram (gm) = 1 kilogram (kg)
 1 quintal = 100 kilogram (kg)
 10 quintal = 1 metric ton = 1000 kg