If a rock is thrown vertically upward from the surface of Mars with velocity of 15 m/s, its height (in meters) after t seconds is h = 15t-1.86t².(a) What is the velocity (in m/s) of the rock after 1 s?11.28 m/s(b) What is the velocity (in m/s) of the rock when its height is 10 m on its way up? On its way down?