when u or v is close to the speed of light that the difference becomes measurable.
Let’s apply the correct formula to our previous example about the spaceship
emitting a pulse of light. With you on the planet and me on the spaceship, u = c.
Naturally, I measure the speed of the light pulse to be v = c, and you would measure
its speed to be
just as Postulate 2 says you must.
Question 14-15
An enemy spaceship of the Empire is traveling toward the planet
Ceti Alpha VI at a speed of 0.4c. The ship emits a beam of
antiprotons at the planet that travel at a speed of 0.5c relative to the
ship.
- How fast are the antiprotons traveling relative to the planet?
- If the Empire ship emits a pulse of red light just before its blast
of antiprotons, with what speed does the red light travel, relative to
the planet?
Here’s How to Crack It
- With u = 0.4c and v = 0.5c, the speed of the antiprotons relative to the
planet is