The doppler effect.
You are welcome.
Answer:
h = 250 m
Explanation:
Given that,
The helicopter exerts 6480 N of force on the water while rising high enough to fly over a mountain.
The helicopter does
of work on the water lifting it.
We need to find how high does it lift the water. Work done is given by :

So, it can lift the water to a height of 250 m.