How far apart from each other would Galileo and his assistant had to have been in order for the round-trip time of their beam of light to equal 1 second?
A) 1500 km
B) 15,000 km
C) 150,000 km
D) 150,000,000 km

Question

Quizplus · Accepted Answer

The speed of light is approximately 300,000 km/s. Therefore, the distance the light travels in one second is 300,000 km. Since the beam of light must travel from Galileo to his assistant and then back, the total distance the light travels is twice the distance between them. Therefore, the distance between them must be 150,000 km (300,000 km round trip divided by 2).

How Far Apart from Each Other Would Galileo and His