**Question:**

**A satellite is to be placed in equatorial geostationary orbit around the earth for communication**

**(a) calculate height of such a satellite**

**(b) find out the minimum number of satellites that are needed to cover entire earth so that at least one satellites is visible from any point on the equator**

**Solution:**

(a) Mass of the earth, M = 6 1024 kg

Radius of the earth, R = 6.4 103 m

Time period = 24 36 102 s

G = 6.67 10-11 N.m2/kg2

Orbital radius = R + h

Using orbital velocity, we can calculate h = 35,940 km

(b) The no.of satellites that are needed to cover the entire earth so that at least one satellite is visible from any point of the equator is 3.