Find the Height yᵢ from Which the Rock Was Launched in a Projectile Motion Problem

A rock is thrown at 9.50 m/s and 30.0° above the horizontal. It travels horizontally d = 18.0 m before hitting the ground. Find its launch height, using g = 9.800 m/s² and neglecting air resistance. Part A: Which trajectory sketch is accurate? The four choices show, respectively: (1) up-right initial velocity, upward acceleration, down-right final velocity; (2) up-right initial velocity, downward acceleration, down-right final velocity; (3) horizontal initial velocity, downward acceleration, vertically downward final velocity; (4) up-right initial velocity, downward acceleration, vertically downward final velocity. All launch above ground and land to the right. Part B: With +x right and +y up, choose the easiest origin: (1) impact point, (2) release point, (3) ground below the trajectory peak, (4) trajectory peak, (5) ground directly below launch point. Part C: Find yᵢ in meters to three significant figures. Part D: A second rock is thrown vertically upward at 4.750 m/s and takes 2.188 s to reach the ground. Find its release height H in meters to three significant figures.