Astronaut rachel leaves earth in a spaceship at a speed of 0.960c relative to an observer on earth. rachel's destination is a star system 14.4 light-years away (one light-year is the distance light travels in one year). according to rachel, how long does the trip take?

Utilizing Lorentz factor;

Lorentz factor = Sqrt (1-u^2/c^2), where u = initial velocity, c = speed of light

But, u/c = 0.960

Therefore,
Lorentz factor = Sqrt (1-0.960^2) = 0.28

For an observer,
t = (Distance to the star*Lorentz factor)/ (u/c) = (14.4*0.28)/0.96 = 4.2 years

Julia would be observing a. static electricity was caused by her sweater rubbing against her shirt and transferring electrons. she didn't touch anything metal, so that would cancel out b.she most likely didn't rub her sweater against her hair either, so that cancels out c.she also didn't scoot across the carpet while trying to take her sweater off, that cancels out d.so that leaves a.a. is correct.