Question

If suddenly the gravitational force of attraction between the earth and a satellite revolving around it becomes zero, then the satellite will

• A. continue to move in its orbit with the same velocity
• B. move tangentially to the original orbit with the same velocity
• C. become stationary in its orbit
• D. move towards the earth

Answer 1

The correct option is B

move tangentially to the original orbit with the same velocity

Explanation for the correct option:

Option B:

1. For a body moving around an object, it is bound by the centripetal force of the object on the body.
2. This force is along the line connecting the body and the object.
3. But the velocity of the body will be perpendicular to this force, which is tangent.
4. When the force of gravity is essentially zero, there is no binding for the satellite to revolve around the earth.
5. Since it moves in the tangent direction with velocity 'v', it continues in the same direction with the same velocity 'v'.

Explanation for the incorrect option:

Option A:

1. In the absence of a centripetal force, the satellite will move tangentially in the original orbit with the instantaneous velocity of the satellite before the force of gravity becomes zero.
2. Thus the satellite will move tangentially and run away from its orbit.

Option C:

1. When the force of gravity becomes zero, the required centripetal force cannot be provided.
2. Therefore, when the force of gravity becomes zero, the satellite moves forward with that instantaneous velocity.

Option D:

1. When the force of gravity becomes zero, the centripetal force on the satellite becomes zero, so the satellite will move tangentially in the original orbit with the same velocity due to the conservation of velocity and energy

Hence, if suddenly the gravitational force of attraction between the earth and a satellite revolving around it becomes zero, then the satellite will move tangentially to the original orbit with the same velocity.

So, option B is correct.