Relativity and angular speed

In summary, the conversation discusses the minimum angular speed needed to produce a streak of light on the moon's surface and why it is not possible to transmit information using this method. The suggested solution is to assume an angle of 90 degrees for the greatest angular speed.
  • #1
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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  • #2
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.
 
  • #3
Ok so I get that w=csin(theta)/d but I still don't have an angle
 
  • #4
You don't need any angle, just assume \theta = 90 deg for the greatest angular speed.
 
  • #5
But how can that be right? C/d just gives me .789 rad/s
 
  • #6
awesome, right?
 

1. What is relativity?

Relativity is a theory developed by Albert Einstein that describes the relationship between space and time. It states that the laws of physics are the same for all observers, regardless of their relative motion.

2. How does relativity affect angular speed?

According to relativity, time and space are relative concepts and can be affected by factors like gravity and acceleration. This means that the angular speed of an object can vary for different observers depending on their relative motion and the effects of gravity in their frame of reference.

3. Can relativity explain why objects appear to move faster when they are closer to us?

Yes, relativity can explain this phenomenon. As an object moves closer to us, it also experiences a change in its frame of reference due to the effects of gravity. This can cause the object to appear to move faster due to a change in its angular speed.

4. How does angular speed change in a rotating frame of reference?

In a rotating frame of reference, the angular speed of an object remains constant. However, due to the effects of relativity, the perceived angular speed of the object may vary for different observers in different frames of reference.

5. Can relativity explain the concept of time dilation?

Yes, relativity can explain time dilation, which is the phenomenon where time appears to pass at a slower rate for objects that are moving at high speeds or in strong gravitational fields. This is due to the effects of relativity on the perception of time in different frames of reference.

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