Question

An astronaut, inside an earth satellite, experiences weightlessness because

• A. no external force is acting on him
• B. he is falling freely
• C. no reaction is exerted by the floor of the satellite
• D. he is far away from the earth's surface

Answer 1

Answer: (B), (C)

no reaction is exerted by the floor of the satellite
he is falling freely

For an earth satellite moving in a circular orbit, centripetal force required for its circular motion is provided by the gravitational force exerted by earth on it.
It means resultant force on the astronaut is equal to the gravitational force exerted by earth on him. Hence, no reaction is exerted by floor of the satellite on him.
In other words, his acceleration towards earth centre (centripetal acceleration) is exactly equal to acceleration caused by the gravitational force alone.
Hence, options (b) and (c) are correct.