Relativity Problem: Sweep Laser for v > c on Moon's Surface

[VitaX]

Homework Statement

You point a laser flahlight to the Moon, producing a spot of light on the moons surface. At what minimum angular speed must you sweep the laser in order for the light spot to streak across the moons surface with speed v > c? Why can't you transmit information between research bases on the Moon with the flying spot?

Homework Equations

The Attempt at a Solution

The problem is utilizing the correct length. I measure it smaller then it is, since I am so far away. but is there a way to calculate that?

 

[Spinnor]

V = omega x R

V = c
R = about 380,000 km
omega = angular velocity in radians/s

For the second part think how you might use the laser on Earth to allow different moon bases to communicate.