3. In a children's story, a princess trapped in a castle wraps a message around a rock and throws it from the top of the castle. Right next to the castle is a moat. The initial velocity of the rock is 12 m/s [42° above the horizontal]. The rock lands on the other side of the moat, at a level 9.5 m below the initial level. Air resistance is negligible. KYU TI A (a) Calculate the rock's time of flight. [ans: 2.4 s] (b) Calculate the width of the moat. [ans: 22 m] (c) Determine the rock's velocity on impact with the ground. [ans: 18 m/s [61° below the horizontal]