Question

Question 2.22 Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):

(a) the total mass of rain-bearing clouds over India during the Monsoon

(b) the mass of an elephant

(c) the wind speed during a storm

(d) the number of strands of hair on your head

(e) the number of air molecules in your classroom.

Class XI Physics Units And Measurements Page 37

Answer 1

(a) finding of mass of rain during Mansoon in India , because it's not constant , you can observe variation time to time . also for finding mass of rain we have require volume of rain and density of rain{ 1 g/cm³ } . but this is fully experimental and general value can obtain by many and many experiment .

(b) finding of Mass of elephant is not easy task , all elephant have no same mass , we can just find out approximate value of it .
by the way
mass of elephant : 680 - 1700 kg

(c) not easy ,but using morden technology we can obtain approximate value . e.g 5m/s - 9 m/s

(d) it is found by using Higher technology , by the way I have no idea , how much strand of hair on my head .

(e) it's can find out easier then above all ,
we first find out volume of class room and then multiply density of class room
then we get MASS of air molecule .
now we use AVOGADRO'S rule and then find out number of molecules of air .