After flying at an altitude of 650 meters, a helicopter starts to descend when its ground distance from the landing pad is 2 kilometers. What is the angle of depression for this part of the flight

The angle of depression is 18.0°

Explanation:

From the question the flight path of the plane is a right angle triangle where the height is 650meters and the length is 2km

Converting 2km to meters gives 2000meters

Therefore the angle of depression = Tan^-1(650/2000)

Angle of depression = Tan^-1(0.325) = 18.0°

pe = weightxheight = 2000x1000=2,000,000joules