Two spaceships are traveling past Earth at 90% of the speed of light in opposite directions (i.e.,they are approaching each other).One turns on a searchlight,which is seen by scientists aboard the other.What speed do the scientists measure for this light (c = speed of light in a vacuum)?

Question

Quizplus · Accepted Answer

According to the principle of relativity, the speed of light in a vacuum is always measured as c, regardless of the relative speeds of the observer and the source of light. Therefore, the scientists aboard the other spaceship will measure the speed of the searchlight as c, even though the spaceship emitting the light is traveling at 90% of the speed of light in the opposite direction.

Two Spaceships Are Traveling Past Earth at 90% of the Speed