Question

Young’s modulus of steel is 1.9 × 10^11 N/m2 . When expressed in CGS units of dynes/cm2, it will be equal to (1N = 105 dyne,1m2 = 104 cm2)
(a) 1.9 × 1010
(b) 1.9 × 1011
(c) 1.9 × 1012
(d) 1.9 × 1013

Answer 1

1.9 * 10¹¹  Newtons/ meter²
 = 1.9 * 10¹¹ * 10⁵ dyne / 10⁴ cm²
 = 1.9 * 10¹² dyne/cm²

Answer 2

Answer:

The correct answer is Option C - $\bold{1.9 \times 10^{12} \mathrm{dyne} / \mathrm{cm}^{2}}$

Explanation:

Dyne and Newton, both are units of force. While Dyne is specified in C-G-S(Centimeter – Gram – Second) unit system, Newton is specified in modern SI unit system which gives the relationship Young’s Modulus between stress and strain. It is used to measure hardness of material.

Here stress is force applied per unit area, strain is deformation happened on object.  

$\mathrm{E}=6 / \epsilon=F / A / \Delta L / L o=\mathrm{Flo} / \mathrm{A} \Delta L$

Where, Ϭ = Stress in Pascal

ϵ = Strain or deformation

F = Force

A = Cross sectioned area

∆L = Change in Length

Lo = Actual Length

E = Young’s Modulus

Here E =  $19 \times 10^{10} \mathrm{N} / \mathrm{m}^{2}$

Let’s convert it into CGS unit system.

E =  $1.9 \times 10^{11}\left(10^{5}\right) \text { dyne } /(100)^{2} \mathrm{cm}^{2}$

$\bold{\mathrm{E}=1.9 \times 10^{12} \mathrm{dyne} / \mathrm{cm}^{2}}$