JEE MainPhysicsGravitationMultiple correct+4 / −1
An astronaut of mass m is working on a satellite orbiting the earth at a distance h from the earth’s surface. The radius of the earth is R, while its mass is M. The gravitational pull FG on the astronaut is :
- AZero since astronaut feels weightless
- B0 < FG <
- C< FG <
- DFG =
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Correct answer: B, D
- Gravitational force at distance from Earth's center
The astronaut is at height above the Earth's surface, so his distance from the center of the Earth is
By Newton's law of gravitation, the gravitational pull on the astronaut is
- Check whether it is zero
Although the astronaut feels weightless, that does not mean gravitational force is zero. Weightlessness in orbit occurs because the astronaut and satellite are in free fall together.
So option A is false.
- Compare with
Since , we have
Therefore,
Also, gravitational force is clearly positive, so
Hence option B is true.
- Check option C
Option C says
But we already found
So the left inequality is not strict; it is actually equal. Therefore option C is false.
- Check option D
From the formula directly,
So option D is true.
Final Answer
Correct options are B and D.
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