computing linear and angular velocities

[thehen]

I need help in computing linear and angular velocities problems such as a beacon rotates at a rate of 3 revolutions per minute. the beacon is located 1km off a straight shoreline. How fast does the beam of light emitted from the beacon appear to be moving to a viewer who is a half a km down the shoreline

 

[Gene]

The angular velocity is 2PI radians per revolution.
You have a right triangle BSV (Beacon to Shore to Viewer).
tan(B)=S/1
Take the derivitive of both sides with respect to t.
You know dB/dt = 6PI radians/minute and you can solve for dS/dt when the beacon angle B=tan^-1(.5) and she sees it.

 

[thehen]

thanks... I can see clearly now I appreciate the help