Radio signals travel at a rate of 3 * 108 meters per second. How many seconds will it take for a radio signal to travel from a satellite to the surface of the Earth if the satellite is orbiting at a height of 7.5 * 106 meters?

The time taken for radio signal to the earth's surface we shall proceed as follows;

time = (distance) / (speed)

Distance=7.5*10^6 meters

speed=3*10^8 meters/second

therefore:

Time = (7.5*10^6) / (3*10^8) = 0.025 seconds

We conclude that it will take the signal 0.025 seconds to reach the surface of the earth.