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## Homework Statement

- A spaceship travels from Earth to the vicinity of the star that is measured by astronomers on Earth to be six light-years away. The spaceship and its occupants have a total rest mass of 32 000 kg. Assume that the spaceship travels at constant velocity. The time taken as measured by clocks on the spaceship is 2.5 years.

- (i) Compute the velocity of the spaceship. [3 marks]

- (ii) How long does the trip take as measured by clocks in the Earth’s

inertial rest frame? [3 marks]

- (i) Compute the velocity of the spaceship. [3 marks]

## Homework Equations

x' = γ(x-ut)

t' = γ(t - ux/c

^{2}) where the dash frame is the object rest frame, u is the relative speed between frames

γ = 1/√(1-u

^{2}/c

^{2})

v' = v-u/1-u

^{2}v/c

^{2}

## The Attempt at a Solution

So I'm a bit stuck my the first part of the question.

So far I have determined that x = 6ly, t' = 2.5yrs. I'm getting a bit puzzled as to what I'm looking to find. Is it u

or v or are they the same thing in this case? regardless I cannot think of a way in which i have enough variables that allows me to compute a value. Any help would be greatly appreciated!