What is Young's modulus ? Explain.

Explanation

Experimental observation show that for a given material the magnitude of the strain produced is same whether the stress is tensile or compressive.
The ratio of tensile (or compressive) stress `(sigma)` to the longitudinal strain `(epsi)` is difined as Young.s modulus and is denoted by the symbol Y.
Young modulus = `("Tensile stress"(sigma))/("Longitudinal strain"(epsi))`
`Y =(sigma)/(epsi)`
`therefore Y = ((F//A))/((Delta L //L))= ((F xx L))/((A xx Delta L))`
Here, strain is a dimensionless quantity, the unit of Young.s modulus is the same as that of stress.
Mean `Nm^(-2)` or Pascal (Pa).
Dimensional formula`:[M^(1) L^(-1) T ^(-2)].`
Young.s moduli, elastic limit and tensile strength of some materials are given below.

For metals Young.s moduli are large therefore these materials require a large force produce small change in length.
Steel is more elastic than copper, brass and aluminium. It is for this reason that steel is preferred in heavy-duty machines and in structural designs.
Wood, bone, concrete and glass have rather small Young.s moduli.