It is a consequence of Newton's law of gravitation that near the surface of any planet, the distance D fallen by a rock in time t is given by 2 D ct = . That is, distance fallen is proportional to the square of the time, no matter what planet one may be on. But the value of c depends on the mass of the planet. For Earth, if time is measured in seconds and distance in feet, the value of c is 16. For objects falling near the surface of a specific planet, if time is measured in seconds and distance measured in feet, the value of c is 5.5. If a rock is dropped from 269.5 feet above the surface of the planet, how long will it take for the rock to strike the ground? a) 4 seconds b) 5 seconds c) 3 seconds d) 7 seconds