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# how long does a spaceship take to travel to alpha centauri? watch

1. How long would a spaceship take to travel from Earth to Alpha Centauri (r.2 light uears away) if its speed were 0.3c? How long does the journey take for the passengers?

I know how to do the second part but for the first part it's t=s/v, do i need to convert s= light years into years?
2. If it's 2 light years away, the distance is c * 2 years in seconds = 299792458 * (60*60*24*365) * 2 = 1.89 * 10^16m

time taken = d/s = 1.89*10^16/(0.3 * 299792458) = 210145380s (6.66 years)
3. A light year is (299792458 * 31557600) m = C*(60*60*24*365.25) not C*(60*60*24*365)
4. It takes two years to get to Alpha Centauri at the speed of light.

c = speed of light

Light Year = distance covered at the speed of light in one year.

If the spaceship is travelling at 0.3c then

years.
A light year is (299792458 * 31557600) m = C*(60*60*24*365.25) not C*(60*60*24*365)
what?? o_O why are you multiplying it by 25?
6. (Original post by Bealzibub)
what?? o_O why are you multiplying it by 25?
Number of days in a year = 365.252.

A light year is (299792458 * 31557600) m = C*(60*60*24*365.25) not C*(60*60*24*365)

Yes.

And it's not C*(60*60*24*365.25)

It's C*(60*60*23.999*365.252)
7. (Original post by Kyx)
Number of days in a year = 365.252.

Yes.

And it's not C*(60*60*24*365.25)

It's C*(60*60*23.999*365.252)
ah okay, I misread the 365.25 part as 365*25
8. (Original post by Bealzibub)
ah okay, I misread the 365.25 part as 365*25
9. No-one has done the time-dilation part of the question yet, about how long it is for the passengers.

Fortunately it doesn't matter, because either the acceleration and deceleration time are so small, they've all been killed by the forces involved, or they're aliens whizzing passed Earth (and Alpha Centauri) without stopping and their years are going to be different.
10. (Original post by unprinted)
No-one has done the time-dilation part of the question yet, about how long it is for the passengers.

Fortunately it doesn't matter, because either the acceleration and deceleration time are so small, they've all been killed by the forces involved, or they're aliens whizzing passed Earth (and Alpha Centauri) without stopping and their years are going to be different.
No-one has pointed out that Alpha Centauri is 4.367 light years from Earth either.

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Updated: February 13, 2016
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