A solid metal bar of uniform diameter D and length L is hung vertically. If ρ is density and E is the young’s then the elongation due to self-weight is
1
\(\frac{{\rho Lg}}{{2E}}\)
2
\(\frac{{\rho L^2g}}{{2E}}\)
3
\(\frac{{\rho Eg}}{{2L^2}}\)
4
\(\frac{{\rho L^2g}}{{E}}\)