Aspaceship travels at a speed of 0.95c to the nearest star, alpha centauri, 4.3 light years (ly) away. how long does the trip take from the point of view of the passengers on the ship?

Two carts, one of mass 2m and one of mass m, approach each other with the same speed, v. when the carts collide, they hook together. assume that positive momentum is to the right. which graph best represents the momentum of both carts over time, before and after the collision?