Q. No.Which of the following diagrams most closely shows the variation in kinetic energy of the Earth as it moves once around the Sun in its elliptical orbit ?
1. 
2. 
3. 
4. 
Starting from the centre of the Earth having radius R, the variation of g (acceleration due to gravity) is shown by:
1.
2.
3.
4.
On doubling the distance between two masses, the gravitational force between them will:
1. remains unchanged.
2. becomes one-fourth.
3. becomes half.
4. becomes double.
Newton's law of gravitation is true for:
1. only uncharged particles.
2. only for planets.
3. only for heavenly bodies.
4. All the bodies.
The gravitational force between two bodies is:
1. repulsive at short distances
2. attractive at large distances
3. repulsive at large distances
4. attractive at all distances
A body is in a state of rest at infinite distance. If it is made a satellite of Earth, which of the following physical quantities will be reduced?
1. Gravitational force
2. Kinetic energy
3. Potential energy
4. Mass.
The Earth is an approximate sphere. If the interior contained matter that is not of the same density everywhere, then on the surface of the Earth, the acceleration due to gravity:
1. will be directed towards the centre but not the same everywhere.
2. will have the same value everywhere but not directed towards the centre.
3. will be same everywhere in magnitude directed towards the centre.
4. cannot be zero at any point.
Which of the following are true?
| 1. | a polar satellite goes around the Earth's pole in West-East direction. |
| 2. | a geostationary satellite goes around the Earth in East-West direction. |
| 3. | a geostationary satellite goes around the Earth in West-East direction. |
| 4. | a polar satellite goes around the Earth in East-West direction. |
As observed from the earth, the sun appears to move in an approximately circular orbit. For the motion of another planet like mercury as observed from the earth, this would:
| 1. | be similarly true. |
| 2. | not be true because the force between the earth and mercury is not inverse square law. |
| 3. | not be true because the major gravitational force on mercury is due to the sun. |
| 4. | not be true because mercury is influenced by forces other than gravitational forces. |
Different points in the earth are at slightly different distances from the sun and hence experience different forces due to gravitation. For a rigid body, we know that if various forces act at various points in it, the resultant motion is as if a net force acts on the centre of mass causing translation and net torque at the centre of mass causing rotation around an axis through the CM. For the earth-sun system (approximating the earth as a uniform density sphere):
| 1. | the torque is zero. |
| 2. | the torque causes the earth to spin. |
| 3. | the rigid body result is not applicable since the earth is not even approximately a rigid body. |
| 4. | the torque causes the earth to move around the sun. |
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