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?
between 300,000 and 400,000 km/s
200,000 km/s
400,000 km/s
between 200,000 and 300,000 km/s
It was D.
Well, let me just say that those galaxies must be in quite a hurry to be moving away from us at such speeds! Now, to answer your question, since each galaxy is moving away from the Earth at 200,000 km/s relative to us, when the observer in one galaxy looks at the other galaxy, they would see it moving away at the same speed as well. So the answer would be 200,000 km/s. They're like two speedy runners sprinting away from each other in opposite directions!
To find the relative velocity between the two galaxies, we need to subtract their individual velocities. Both galaxies have a velocity of 200,000 km/s relative to the Earth, but since they are moving away from each other, we need to consider the velocities with opposite signs.
Therefore, the relative velocity between the two galaxies would be 200,000 km/s - (-200,000 km/s) = 400,000 km/s.
So, an observer in one of those galaxies would see the other galaxy moving away at a speed of 400,000 km/s.
The correct answer is 400,000 km/s.
To determine how fast an observer in one galaxy would see the other galaxy moving away, we need to consider the concept of relative velocities. The observer in one galaxy will perceive the velocity of the other galaxy as the difference between their own velocity relative to the Earth and the velocity of the other galaxy relative to the Earth.
Given that each galaxy has a velocity of 200,000 km/s relative to the Earth, we can determine the velocity perceived by the observer in one of the galaxies by subtracting their own velocity from the velocity of the other galaxy.
So, the velocity perceived by the observer in one of the galaxies would be:
200,000 km/s (velocity of the other galaxy) - 200,000 km/s (velocity of their own galaxy) = 0 km/s
This means that the observer in one of the galaxies would perceive the other galaxy as stationary or not moving at all. Therefore, the correct option is between 200,000 and 300,000 km/s, as the perceived velocity would be 0 km/s.
C
since the speeds are low relative to the speed of light.