Final answer:
Helicopters use rotational kinetic energy in their blades to sustain flight, and a tail rotor or counter-rotating blades to prevent the body from spinning in the opposite direction. Newton's third law explains the need for these mechanisms. Maintaining sufficient rotational kinetic energy is crucial as the helicopter engines are not powerful enough to quickly restore it if it drops below a critical level.
Step-by-step explanation:
Understanding Helicopter Rotational Kinetic Energy and Blade Rotation
Helicopters store rotational kinetic energy in their main lift blades, which is essential for maintaining flight. To stabilize the helicopter and prevent its body from spinning due to conservation of angular momentum, a small tail rotor provides necessary thrust. However, in helicopters with two sets of lifting blades, these blades rotate in opposite directions, eliminating the need for a tail rotor. This counter-rotation balances the torques and thus prevents the helicopter from spinning uncontrollably.
According to Newton's third law of motion, every action has an equal and opposite reaction. Thus, as the main lifting blades rotate in one direction, they create an equal and opposite force, causing the helicopter body to want to rotate in the opposite direction. The tail rotor counters this effect, or in twin rotor designs, the opposing rotations of the two blade sets balance out the forces.
Pilots must also manage the rotational kinetic energy of the blades. If the blades slow down below a critical angular velocity, the helicopter loses lift. Because helicopter engines have limited power and weight capacities, they cannot easily replenish the rotational kinetic energy and provide lift simultaneously. Therefore, it's critical to maintain the energy needed to prevent loss of control or a crash.