Weightlessness

NCERT Class 11, Chapter 8 (Gravitation) clarifies that weightlessness in orbit is not due to an absence of gravity. At typical orbital altitudes Earth's gravity is only slightly weaker than at the surface and is in fact what keeps the satellite in orbit. The sensation of weight comes from a normal reaction force; in orbit both the astronaut and spacecraft accelerate toward the Earth at the same rate, the local $g$, so the floor exerts no normal force on the astronaut. With zero normal reaction, the apparent weight is zero, which is the state of free fall. The claim that gravity is absent is false, since gravity supplies the centripetal force. Shielding is impossible because no material blocks gravity. Mass is an intrinsic property and never becomes zero. As a plausibility check, the same effect is felt momentarily in a freely falling lift on Earth, confirming that shared free-fall acceleration, not loss of gravity, produces weightlessness.