Satellites orbiting the earth have a finite life and sometimes debris of satellites fall to the earth. This is because a) the solar cells and batteries in satellites run out b) the laws of gravitation predict a trajectory spiralling inwards c) of viscous forces causing the speed of the satellite and hence height to gradually decrease d) of collisions with other satellites
Correct option is C) the P.E. of satellite orbiting in orbit of radius r due to earth of mass M is (2r−GM) negative sign shows the forces of attraction between satellite and earth . energy (P.E.) is continuously reduced due to atmospheric friction , the radius of the orbit or height decreases gradually and ultimately it comes back to earth with increasing speed and burns in the atmosphere. Hence option C
