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):

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

Solution

Area of the head surface carrying hair = A
Radius of hair strand can be measured using a screw gauge.
Let radius of the hair strand be 'r'.

Area space of space 1 space hair space equals space πr squared space No. space of space strands space of space hair space equals space fraction numerator Total space surface space area over denominator Area space of space one space hair space end fraction space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals space fraction numerator straight A over denominator space πr squared space end fraction

Some More Questions From Units and Measurement Chapter

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