Final answer:
Lift in helicopters is generated by rotor blades exerting force on air, creating an upward force through Newton's third law. Helicopters store critical rotational kinetic energy in their blades, which must be maintained to prevent loss of lift and potential crashes. Understanding lift involves factors beyond simple airflow dynamics due to the complex nature of aerodynamics.
Step-by-step explanation:
In the case of helicopters, lift is produced by rotor blades moving through the air at a speed sufficient to create lift. These blades work by pushing air downwards, generating an upward reaction force due to Newton's third law of motion - for every action, there is an equal and opposite reaction. This is similar to how birds and airplanes achieve flight, by exerting a force on the air in a direction opposite to the force they require to lift off and move forward.
Helicopters store rotational kinetic energy in their blades, which is essential to achieve lift. The engines must impart enough energy to the blades before takeoff to maintain this rotational energy throughout the flight. Helicopter pilots understand that if the blades' rotational energy falls below a critical level, they risk losing lift and potentially crashing. To avoid this, they might use the helicopter's gravitational potential energy in a controlled descent to spin up the blades enough to regain lift before reaching the ground.
Important Note on Lift Mechanics
However, factors such as air density, body design, and engine thrust also contribute to an aircraft's lift, and the complexity of the airflow, including turbulence, means that Bernoulli's principle only provides an approximate understanding of lift mechanics.