Originally Posted by

**AtruDiva** A space probe of the surface of Mars sends a radio signal back to the

Earth,a distance of 3.79 x 1010 km. Radio waves travel at the

speed of light (3.00 x 108 m/s).

(a) How far away is the space probe?

(b) How many seconds does it take for the signal to reach the Earth?

(c) How many hours is this?

(a) - you are told that the probe is on Mars, and that Mars is 3.79 x 10^10 Km away. So the answer is obvious.

(b) Remember the basic equation for distance, velocity and time: d = v*t. Here you know d (distance) and v (velocity of light, which is 3 x 10^8 m/s), so now you can calculate t (time). This will give t in the unit of seconds.

(c) Convert time in seconds to time in hours by dividing by 3600 seconds per hour.