Special Relativity Help (1 Viewer)

[the-derivative]

Hey guys,

I was doing some past papers and I came about this question and got stuck. I was wondering if you could help me with this question.

After the sun, the nearest visible star visible to the naked eye is Rigel Centaurus which is 4.35 light years away. If a spacecraft was sent there from Earth at a speed of 0.80c, how many years would it take to reach that star from Earth as measured by observers

(a) on Earth,
(b) on the spacecraft and
(c) what is the distance traveled according to the observers on the spacecraft.

Thanks in advance guys. =)

 

[jyu]

(a) 4.35/.8 = 5.44 years

(b) Proper time = 5.44 x (1 - 0.8^2)^0.5 = 3.26 years

(c) Contracted length = 4.35c x (1 - 0.8^2)^0.5 = 2.61c metres

 

[ozzievictor]

Could this be a trick question - 9.79 years being 5.44 travel time plus 4.35 before they see it arrive as light takes 4.35 years to get back to earth at which time the earth observer clicks the stop watch?

 

[lolokay]

I don't think it would be a trick