The gravitational pull of the earth on an object is inversely proportional to the square of the distance of the object from the center of the earth. At the earth s surface this force is equal to the object s normal weight mg, where g = 9.8 m/s2, and at large distances, the force is zero. If a 20,000-kg asteroid falls to earth from a very great distance away, what will be its minimum speed as it strikes the earth s surface, and how much kinetic energy will it impart to our planet? You can ignore the effects of the earth s atmosphere. |

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