Young's modulus of steel is $1.9 \times 10^{11}\, N \,m^{-2}$ . When expressed in $CGS$ units of dynes $cm^{-2}$ , it will be equal to ( $1 \,N = 10^5$ dyne, $1\, m^2 = 10^4\, cm^2$ )

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.

Young's modulus of steel is $1.9 \times 10^{11}\,

Notes on Units and measurement

Concepts Used:

Units and Measurement

Unit:

A unit of a physical quantity is an arbitrarily chosen standard that is broadly acknowledged by the society and in terms of which other quantities of similar nature may be measured.

Measurement:

The process of measurement is basically a comparison process. To measure a physical quantity, we have to find out how many times a standard amount of that physical quantity is present in the quantity being measured. The number thus obtained is known as the magnitude and the standard chosen is called the unit of the physical quantity.

System of Units:

CGS system
FPS system
MKS system
SI units

Types of Units:

Fundamental Units -

The units defined for the fundamental quantities are called fundamental units.

Derived Units -

The units of all other physical quantities which are derived from the fundamental units are called the derived units.

Young's modulus of steel is $1.9 \times 10^{11}\, N \,m^{-2}$. When expressed in $CGS$ units of dynes $cm^{-2}$, it will be equal to ($1 \,N = 10^5$ dyne, $1\, m^2 = 10^4\, cm^2$)

The Correct Option is C

Solution and Explanation

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