A helicopter starting from rest accelerates straight up from

A helicopter starting from rest, accelerates straight up from the roof of a hospital. The lifting force does work on the helicopter. An 810 - kg helicopter rise from rest to a speed of 7.0 m/s in a time of 3.5 seconds. During this time it climbs to a height of 8.2 m. What is the average power generated by the lifting force

Solution

Acceleration = (v^2/2h) = 2.9878m/sec^2.
Total acceleration = (2.9878 + 9.8) = 12.7878m/sec^2.
Force = (ma) = 810 x 12.7878, = 10,358.12N.
Work = (fh) = 10,358.12x 8.2, = 84,936.584 Joules.
Average power = (84,936.584/3.5) = 24,267.59 Watts, or 24.267kW.