A star is at rest relative to earth and at a distance of 1500 light-years. An as

Question

A star is at rest relative to earth and at a distance of 1500 light-years. An astronaut wishes to travel from earth tot he start and age no more than 30 years during the entire round-trip journey.

1, Assuming that the journey is made at constant speed and that the acceleration and deceleration intervals are very short compared with the rest of the journey, what speed is necessary for the trip?

2, according to the astronaut, what is the distance from earth to the star?

3,accoring to someone on earth, how long does it take the astronaut to make the round trip?

4, it takes light 1500 years to travel from earth to the star, but the astronaut makes the trip in 15 years. Does this mean that the astronaut travels faster thatn light? explain your answer

Explanation / Answer

1) 0.99995c You are trying to make gamma = 1/(1 - v2/c2)1/2 = 100 in order to shrink 1500 ly to 15 years, which means v/c = 0.99995

2) 15 ly. He is travelling at essentially the speed of light, or almost (0.99995c), and the Lorzentz contration divides the actual distance of 1500 ly by gamma, giving 15 ly.

3) 3000.15 years (3000 ly / 0.99995 c)

4) No, he is travelling very slightly slower than light. It only takes the astronaut 15 years in his own frame of reference, but since in that frame the distance is 15 ly, he also agrees that he is travelling just slightly slower than light.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.