Suppose you are an astronaut and you have been stationed on a distant planet. You would like to find the acceleration due to the gravitational force on this planet so you devise an experiment. You throw a rock up in the air with an initial velocity of 7 m/s and use a stopwatch to record the time it takes to hit the ground. If it takes 8.0 s for the rock to return to the same location from which it was released, what is the acceleration due to gravity on the planet?