I'm doing the following problem:
A castle on a cliff has a cannon 300m above sea level. The cannon can shoot a 10kg iron ball with a velocity of 400 m/s . If the cannon is raised to an angle 30º of above the horizon, calculate the following:
the final velocity of the cannon ball just before it strikes the water
I know final Vy will be negative since it points down but doing the maths Vfinal is positive (and I think should be negative because it points down) and θ is negative. Is it correct? if yes. Why is θ negative?