Re: Rel. Speed

Dear razyrel:

"razyrel" <razyrel@xxxxxxxxxxxxxxxxxx> wrote in message
news:f5v5pe$4ik$1@xxxxxxxxxxx
Suppose a spaceship is moving at a constant speed of 0.8c.
Then the ship sends a pulse of light to the same direction
as of the ship.
Questions:
a) Will the speed of this pulse of light be c or c-0.8=0.2c ?

The ship would measure it as c. A stationary observer would
measure it as travelling at c. The only possible light speed
measurements require a two-way light path (of one form or
another).

b) How is it to interpret from the ship's frame of reference?

c. Always c.

c) How is it to interpret from the frame of reference of a
stationary viewer

c. Always c.

who is in a distance at a right angle parallel to the ships
route when the light knob was pushed?

c. Always c.

http://hermes.physics.adelaide.edu.au/~dkoks/Faq/
http://hermes.physics.adelaide.edu.au/~dkoks/Faq/Relativity/SpeedOfLight/headlights.html

David A. Smith


.

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