a) What is the minimum speed with which a meteor strikes the top of Earth's stratosphere (about 43.5 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 10-11 N-m/kg b) An ideal spring has a spring constant k = 28.3 N/m. What is the amount of work that must be done to stretch the spring 0.500 m from its relaxed length?