Chapter SH, Problem 9.7MPS

To determine

To calculate: To find the area of cross section of hair and write the answer in scientific notation.

Answer to Problem 9.7MPS

The area of cross section of hair is $50.24\times {10}^{-6}$ square centimetre.

Explanation of Solution

Given: The average width of human hair is $4\times {10}^{-3}$ centimetre and the cross section of the average hair is round

Formula Used:

Area of circle is given as

  $A=3.14\times r^2$

Where, $r=$ Radius of circle

Calculation:

Given average width of human hair is $4\times {10}^{-3}$ centimetre.

Also, the cross section of the average hair is round

Thus, radius of circle is

  $r=4\times {10}^{-3}$

Area of cross section of hair is calculated as

  $\begin{array}{l}A=3.14\times {\left(4\times {10}^{-3}\right)}^2\\ A=3.14\times {\left(4\right)}^2\times {\left({10}^{-3}\right)}^2\\ A=3.14\times 16\times {10}^{-6}\\ A=50.24\times {10}^{-6}\end{array}$

Conclusion:

Hence, the area of cross section of hair is $50.24\times {10}^{-6}$ square centimetre.