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

Options

A. The solar cels and batteries in satellites run out
B. the laws of gravitation predict a trajectory spiralling inwards.
C. of viscous forces causing the speed of satellite and hence height to gradually decrease
D. of collisions with other satellites

Answer

C

Explanation

We known that the total energy of the earth satelite of radius R bounced system is negative `((-GM)/(2R))`
Where M is mass of the earth.
Due to the atmospheric fircition (viscous force) acting on satellite, energy decreases continuosuly, radius of het orbit or height decreases gradually and tehsatellite spirals dwn with increasing speed till it burns in the denser layers of the atmosphere.