CBSE Class 9 Answered

Weightlessness (or zero-g) is the condition that exists for an object or person when they experience little or no acceleration away from the acceleration that defines an inertial trajectory, or the trajectory of pure free-fall.The presence of a gravitational field will cause a free body to follow the accelerated trajectory of a free fall in gravity, and weightlessness will also be experienced during any such naturally-accelerated free fall.As an example, an accelerated free fall trajectory allows the weightlessness of objects in a falling elevator.