Gravitation Physics - Gravitation

The acceleration of the moon just before it strikes the earth in the previous question is :

Let V and E represent the gravitational potential and field at a distance r from the centre of a uniform solid sphere. Consider the two statements:

1. The plot of V against r is discontinuous.
2. The plot of E against r is discontinuous.

1. Both A and B are correct.
2. A is correct but B is wrong.
3. B is correct but A is wrong.
4. Both A and B are wrong.

Inside a uniform spherical shell:

1. The gravitational potential is zero.
2. The gravitational field is zero.
3. The gravitational potential is same everywhere.
4. The gravitational field is same everywhere.

The magnitude of gravitational potential energy of the moon-earth system is U with zero potential energy at infinite separation. The kinetic energy of the moon with respect to the earth is K.

1. U < K
2. U > K
3. U = K

A tunnel is dug along a diameter of the earth. Find the force on a particle of mass m placed in the tunnel at a distance x from the centre.

Find the height over the earth's surface at which the weight of a body becomes half of its value at the surface.

Two spherical balls of mass 10kg each are placed 10cm apart. Find the gravitational force of attraction between them.

A nut becomes loose and gets detached from a satellite revolving around the earth. Will it land on the earth? If yes, where will it land? If no, how can an astronaut make it land on the earth?

The earth revolves round the sun because the sun attracts the earth. The sun also attracts the moon and this force is 'about twice as large as the attraction of the earth on the moon. Why does the moon not revolve round the sun? Or does it?

A body stretches a spring by a particular length at the earth's surface at equator. At what height above the south pole will it stretch the same spring by the same length? Assume the earth to be spherical.

The weight of an object is more at the poles than at the equator. Is it benificial to purchase goods at equator and sell them at the pole? Does it matter whether a spring balance is used or an equal-beam balance is used?

Can two particles be in equilibrium under the action of their mutual gravitational force? Can three particles be? Can one of the three particles be?

The weight of a body at the poles is greater than the weight at the equator. Is it the actual weight or the apparent weight we are talking about? Does your answer depend on whether only the earth's rotation is taken into account or the flattening of the earth at the poles is also taken into account?​​​​​

Is there any meaning of "Weight of the earth"?

No part of India is situated on the equator. Is it possible to have a geostationary satellite which always remains over New Delhi?

A solid sphere of mass m and radius r is placed inside a hollow thin spherical shell of mass M and radius R as shown in A particle of mass m' is placed on the line joining the two centres at a distance x from the point of contact of the sphere and the shell. Find the magnitude of the resultant gravitational force on this particle due to the sphere and the shell if,

1. r < x < 2r.
2. 2r < x < 2R.
3. x > 2R.

Three equal masses m are placed at the three corners of an equilateral triangle of side a. Find the force exerted by this system on another particle of mass m placed at,

1. The mid-point of a side,
2. At the centre of the triangle.

Four particles having masses m, 2m, 3m and 4m are placed at the four corners of a square of edge a. Find the gravitational force acting on a particle of mass m placed at the centre.