1. A helicopter was hovering at an altitude of 15 km when a panel from below slipped off and fell to the ground (Figure below). The mass of the panel is 14 kg, and it hits the ground with a speed of 35 m/s. How much mechanical energy is dissipated by air resistance while the panel is descending? (please answer with steps and details.)

Panel falls from this height E U K =0 Terminal velocity reached here E U K E has decreased; U has decreased; K is constant