What is the minimum speed with which a meteor strikes the top of Earth's stratosphere (about 48.0 km above the surface), assuming that the meteor begins as a bit of interplanetary debris far from Earth and stationary relative to Earth? Assume that the drag force is negligible until the meteor reaches the stratosphere. Mass of Earth is 5.974 10²⁴ kg;radius of Earth is 6.371 10⁶ m; and gravitational constant is 6.674 10¹¹ Nm²/kg².

_____km/s