Physics 1 question. Need major help pleasee. 10 ptss?

A 6500 kg railroad car moving at 4.0 m/s couples with a second 7500 kg car initially at rest. a) Sketch before and after pictures of the situation. b) What assumptions do you need to make so that conservation of momentum holds? c) Find the final velocity of both cars. d) Find the ratio of final to initial kinetic energy? Explain why this ratio should be less than 1. e) What is the change in momentum of the second car? f) If the collision lasted for 0.2 s, what is the average force exerted on the second car? g) How does it compare to the average force exerted on the first car. Explain your answer.