When a rocket is 2 kilometers high, it is moving vertically upward at a speed of 300 kilometers per hour. At that instant, how fast is the angle of elevation of the rocket increasing, as seen by an observer on the ground 5 kilometers from the launching pad?
( Hint: The angle of elevation is the angle between the horizontal ground and the line of sight with respect to the rocket. )
When the rocket is 9 kilometers high, the angle of elevation from the observer is changing at a rate of radians per hour.