An astronaut set out in a spaceship from Earth orbit to travel to a distant star in our galaxy. The spaceship travelled at a speed of 0.8 c. When the spaceship reached the star the on-board clock showed the astronaut that the journey took 10 years.
An identical clock remained on Earth. What time in years had elapsed on this clock when seen from the astronaut's spaceship?
(A) 3.6
(B) 6.0
(C) 10.0
(D) 16.7
Why is this question invalid?
Can't we say that the answer is D?
The reason being:
The astronaut can consider the earth as moving and the spaceship/himself as stationary. Thus, from his point of view, the time on the earth is dilated, being 16.7 years when the time in the spacehip is only 10 years.
Hmm.. wait.. after I typed it up it started to become confusing... and now I think using the above argument it gives B as the answer.
But it assumes that the ship never accelerates, so it has always travelled at 0.8 c (which is not possible because there was a time when the manufacturing had just been completed and the ship and the earth were not moving relative to each other)
An identical clock remained on Earth. What time in years had elapsed on this clock when seen from the astronaut's spaceship?
(A) 3.6
(B) 6.0
(C) 10.0
(D) 16.7
Why is this question invalid?
Can't we say that the answer is D?
The reason being:
The astronaut can consider the earth as moving and the spaceship/himself as stationary. Thus, from his point of view, the time on the earth is dilated, being 16.7 years when the time in the spacehip is only 10 years.
Hmm.. wait.. after I typed it up it started to become confusing... and now I think using the above argument it gives B as the answer.
But it assumes that the ship never accelerates, so it has always travelled at 0.8 c (which is not possible because there was a time when the manufacturing had just been completed and the ship and the earth were not moving relative to each other)
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