NCERT Solutions for Chapter: Gravitation, Exercise 1: MCQ-I

The earth is just an approximate sphere. If the interior contained matter which is not of the same density everywhere, then on the surface of the earth, the acceleration is due to gravity.

As observed from earth, the sun seems to move in an approximately circular orbit. For the motion of another planet like mercury as observed from earth, this would

Different points in the earth are at slightly different distances from the sun and hence experience different forces owing 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 c.m (centre of mass) causing translation and net torque at the c.m causing rotation around an axis through the c.m. For the Earth-Sun system (approximating the earth as a uniform density sphere)

Satellites orbiting the earth have a finite life and sometimes debris of satellites fall to the earth. This is because,

Both earth and moon are subject to the gravitational force of the sun. As observed from the sun, the orbit of the moon.

Particles of masses $2M, m and M$are respectively at points $\mathrm{A}, \mathrm{B}$ and $\mathrm{C}$, distance $AB=\frac{1}{2}\left(BC\right),m<<M$ and at time, $t=0$, they are all at rest (as shown in the figure). At subsequent times before any collision takes place: