Two galaxies on opposite ends of the universe are moving away from the Earth. Each has a velocity of 200,000 km/s relative to the Earth. How fast would an observer in one of those galaxies see the other galaxy moving away? (1 point)

Question

Responses

between 200,000 and 300,000 km/s
between 200,000 and 300,000 km/s

between 300,000 and 400,000 km/s
between 300,000 and 400,000 km/s

200,000 km/s
200,000 km/s

400,000 km/s

Answer 1

The correct answer is between 400,000 and 500,000 km/s.

When two galaxies are moving away from each other, their relative velocity is the sum of their individual velocities. In this case, both galaxies have a velocity of 200,000 km/s relative to the Earth. Therefore, an observer in one of those galaxies would see the other galaxy moving away with a velocity of 200,000 km/s + 200,000 km/s = 400,000 km/s.