A Projectile Is Fired from Point 0 at the Edge

Short Answer

A projectile is fired from point 0 at the edge of a cliff, with initial velocity components of
and
, as shown in the figure.The projectile rises and then falls into the sea at point P. The time of flight of the projectile is 40.0 s, and it experiences no appreciable air resistance in flight. What is the magnitude of the velocity of the projectile 21.0 s after it is fired?