For a solid rod, the Youngs modulus of elasticity is \( 3.2 \times 10^{11} \, \text{N m}^{-2} \) and density is \( 8 \times 10^{3} \, \text{kg m}^{-3} \). The velocity of longitudinal wave in the rod will be:
\( 145.75 \times 10^{3} \, \text{m s}^{-1} \)
\( 18.93 \times 10^{3} \, \text{m s}^{-1} \)
\( 6.32 \times 10^{3} \, \text{m s}^{-1} \)
\( 3.65 \times 10^{3} \, \text{m s}^{-1} \)