An FAL rifle has a 0.533 m long barrel. When fired, a bullet with a mass of 10.0 g accelerates from rest and exits the barrel at a speed of 840 m/s. What is the net force on the bullet (in N) while it is in the barrel

According to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does maria's voyage take according to samir?