Question

Satellite dishes do not have to change direction in order to stay focussed on a signal from a satellite. This means that the satellite always has to be found at the same location with respect to the surface of earth. For this to occur, the satellite must be at a height such that its revolution ** is the same as that of earth 24 h. At what height must a satellite be to achieve this?

Answer 1

The correct option is (a).

Explanation:

The force that produces the centripetal acceleration of the satellite is the gravitational force, so

where, Me is earth' mass and r is the satellite' distance from the centre of earth.

Also, we find the speed of the satellite to be

where, T is the orbital ** of the satellite.

Solving Eqs. (i) and (ii) simultaneously for r yields