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**1. Homework Statement**

A spaceship departs from Earth for the star Alpha Centauri whic is 4 light years away. The spaceship travels at .75c. Howlong does it take to get there (a) as measured on Earth and (b) as measured by by a passenger on the spaceship

**2. Homework Equations**

proper time = delta(t')=2D/v

delta(t)=delta(t')/sqrt(1-v^2/c^2)

**3. The Attempt at a Solution**

In part a, the observer is going to the measured that the earth travels at the speed of light, so I would used the equation , delta=delta(t')/sqrt(1-v^2/c^2)

In part b, the observer on the space ship is going to measured the proper time and will not notice that the spaceship is traveling closed to the speed of light . so he will used the equation delta(t') =2D/v= 2*(4*light*years)/(.75c)

Are both my observations correct?