Can a Laser Beam Move Faster Than Light Across the Moon's Surface?

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Homework Help Overview

The discussion revolves around the angular speed required for a laser beam to sweep across the surface of the Moon at a speed greater than the speed of light. Participants are exploring the implications of this scenario and the limitations of transmitting information using the laser spot.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to determine the necessary angular speed for the laser beam and questioning the assumptions regarding the distance to the Moon and the angle of the beam. There is a discussion about using an angle of 90 degrees for maximum angular speed.

Discussion Status

The conversation is ongoing, with participants sharing their thoughts on the calculations and assumptions involved. Some guidance has been offered regarding the angle and the relationship between angular speed and linear speed, but there is no clear consensus on the correct approach or interpretation of the problem.

Contextual Notes

There is a noted lack of specific information, such as the distance to the Moon and the angle of the laser beam, which is affecting the participants' ability to arrive at a solution.

briteliner
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Homework Statement



You point a laser flashlight at the moon producing a spot of light on its surface. At what minimum angular speed must you sweep the laser beam in order for the light spot to streak across the moon's 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


I figure I need to find an angle but I don't get how since there is not much info given in the problem
 
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It's probably assumed you know the distance to the Moon d. Then just find the angular velocity for the spot to travel at the speed of light c.
 
Ok so I get that w=csin(theta)/d but I still don't have an angle
 
You don't need any angle, just assume \theta = 90 deg for the greatest angular speed.
 
But how can that be right? C/d just gives me .789 rad/s
 
awesome, right?
 

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