Question

A brass wire 1m long and 1mm diameter is stretched with the weight of 2kg. Find the elongation of the wire. Given, Y for brass = 1×10¹² dyne cm-²dyne​

Answer 1

Given

Length of wire = 1 m = 100 cm

Diameter of the wire = 1 mm = 0.1 cm

Mass of the wire = 2 kg

Thus weight of the wire = Force = 2 × 10 = 20 kg/cm²

Young Modulus of the wire Y = 1 × 10 ⁻¹²

We know Y =(stress σ/strain ε) -----(A)

We know σ =Force/ Area = 20/3.14× 0.1² = 636.942

Again we know strain ε = δL/L -----(B)

Now reducing the above found values in (A)

δL= (Lσ)/Y

δL= (100×636.942 )/1 × 10 ⁻¹² = 0.636×10⁻⁹