Question
Young's modulus of steel is $$1.9 \times {10^{11}}N/{m^2}.$$ When expressed in CGS units of $$dyne/c{m^2},$$ it will be equal to $$\left( {1\,N = {{10}^5}dyne,1\,{m^2} = {{10}^4}c{m^2}} \right)$$
A.
$$1.9 \times {10^{10}}$$
B.
$$1.9 \times {10^{11}}$$
C.
$$1.9 \times {10^{12}}$$
D.
$$1.9 \times {10^{13}}$$
Answer :
$$1.9 \times {10^{12}}$$
Solution :
It is given that Young's modulus $$\left( Y \right)$$ is,
$$\eqalign{
& Y = 1.9 \times {10^{11}}\,N/{m^2} \cr
& 1\,N = {10^5}dyne \cr
& {\text{So,}}\,\,Y = 1.9 \times {10^{11}} \times {10^5}\,dyne/{m^2} \cr} $$
Convert meter to centimeter $$\because 1\,m = 100\,cm$$
$$\eqalign{
& Y = 1.9 \times {10^{11}} \times {10^5}\,dyne/\left( {{{100}^2}\,c{m^2}} \right) \cr
& \,\,\,\,\,\, = 1.9 \times {10^{12}}\,dyne/c{m^2} \cr} $$