In episode 5 of Star Wars the Empire’s spaceships launch probe droids throughout
ID: 1571865 • Letter: I
Question
In episode 5 of Star Wars the Empire’s spaceships launch probe droids throughout
the galaxy to seek the base of the Rebel Alliance. Suppose a spaceship moving at
2.3 * 108 m/s toward Hoth (site of the rebel base) launches a probe droid toward Hoth at
2.1 * 108 m/s relative to the spaceship. According to Galilean relativity: (a) What is the
speed of the droid relative to Hoth? (b) If rebel astronomers are watching the approaching
spaceship through a telescope, will they see the probe before it lands on Hoth?
Explanation / Answer
a) the speed of the droid relative to Hoth = (vb - va)/(1 - vbva/c2)
= (2.3 * 108 - 2.1 * 108)/(1 - 2.3 * 2.1/9)
= 4.316 * 107 m/s
b) If rebel astronomers are watching the approaching spaceship through a telescope, they will not see the probe before it lands on Hoth .