An interstellar ship has a mass of 1.20 X10^6 kg and is initially at rest relative to a star system. a) what constant acceleration is needed to ring the ship up to a speed of .10c (where c is the speed of light, 3.0X10^8 m/s) relative to the star system in 3 days? b) what is that acceleration in g units? c) what force is required for the accelaration? d) If the engines are shut down when .10c is reached (the speed then remains consant) how long does the ship take (start to finish) to journey 5 light months the distance that light travels in 5 months?

I found this question to be quite difficult will you please clearify each part of the question for me? I couldn't figure out what to do.

You can go to wikipedia and read the article "Special relativity", specifically sections:

"Velocity and acceleration in 4D"

and

"Force in 4D"