Question

What hanging mass will stretch a 2.8-m-long, 0.60 mm - diameter steel wire by 1.5 mm ? the young's modulus of steel is 20×1010n/m2?

Answer 1

let the force be F
area of cross section(A) = π×{6×10^(-4)}^2 m^2
length (L) = 2.8 m
change in length (l) = 1.5×10^(-3) m
Y = 2×10^(11) n/m^2

F = Y× (l/L) × A

you calculate it. Just put the values as I have written. you will get the Answer in Newton