Take into account that the kinetic energy is given by the following formula:
[tex]K=\frac{1}{2}mv^2[/tex]where,
m: mass of the asteroid = 700*10^6 kg = 7*10^8 kg
v: speed of the asteroid = 19000 m/s
Replace the previous values of the parameters into the formula for K and simplify:
[tex]\begin{gathered} K=\frac{1}{2}(7\cdot10^8kg)(19000\frac{m}{s})^2 \\ K\approx2.5\cdot10^{17}J \end{gathered}[/tex]Hence, approximately 2.5*10^17 J of energy would be released when the asteroid impacts the Earth