An asteroid is moving directly towards the centre of the earth. When at a distance of $10R$ ($R$ is the radius of the earth) from the centre of the earth, it has a speed of $12\,\mathrm{km\,s^{-1}}$. Neglecting the effect of earth's atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is $11.2\,\mathrm{km\,s^{-1}}$)? Give your answer to the nearest integer in $\mathrm{km\,s^{-1}}$ $\underline{\hspace{1cm}}$.