An astronaut holds a rock 100 m above the surface of Planet X. The rock is then thrown upward with a speed of 15 m/s, as shown in the figure. The rock reaches the ground 10 s after it is thrown. The atmosphere of Planet X has a negligible effect on the rock when it is in free fall. 15 m/s 100 m (i) Determine the acceleration due to gravity of the rock when it is on Planet X. ii. How does the speed of the rock when it reaches the ground Ud compare to the speed of the rock when it is thrown upward Vu ? "a < Pa "a = Pa "a > Pa State your reasoning. (b) A student wants to know how the motion of the rock would be different if it was thrown upward at 15 m/s from a height of 100 m above Earth's surface. In a clear, coherent, paragraph-length response that may also contain figures and/or equations, explain how the motion of the rock on Earth will be different from its motion on Planet X in terms of its maximum height above the ground, the speed at which it reaches the ground, the time in which it is in free fall, and its acceleration due to gravity.