When a helicopter lands on the same spot while the Earth is rotating, it is because the helicopter and the Earth share the same rotational motion. The principles of physics governing the motion of the helicopter and the Earth allow for this to happen.
Here's an explanation:
Conservation of Angular Momentum: The Earth's rotation is characterized by its angular momentum, which is conserved in the absence of external torques. Similarly, a helicopter in flight possesses its own angular momentum. As long as no external forces or torques act on the helicopter, its angular momentum remains constant.
Inertial Frame of Reference: When the helicopter is hovering in the air, it remains in the same inertial frame of reference as the Earth's surface. Inertial frames of reference are frames where Newton's laws of motion hold true without the need to consider additional forces due to the motion itself.
Compensation for Earth's Rotation: To land on the same spot, the helicopter must compensate for the Earth's rotation during its descent. Pilots achieve this by using navigation systems that take into account the helicopter's own velocity and altitude, as well as the Earth's rotational velocity at the given latitude. By adjusting the helicopter's position and flight path, the pilot ensures that the helicopter maintains its relative position above the desired landing spot, even as the Earth rotates beneath it.
In practice, helicopters usually rely on navigational instruments, such as GPS (Global Positioning System), inertial navigation systems, and other onboard technologies to accurately determine their position and compensate for the Earth's rotation during landing.
So, while the Earth is indeed rotating, a helicopter can land on the same spot by maintaining its own angular momentum and compensating for the Earth's rotation during the descent, using navigational systems to ensure precision.