You are a traffic accident investigator. You have arrived at the scene of an accident. Two cars of equal mass (1,000 kg each) were involved in a rear-end accident at a stop sign. Here is what you know: Car 1 approached the intersection from the top of a 25-meter hill. Car 2 was on a flat stretch of road directly in front of Car 1. At the bottom of the hill, Car 1 was going 20 m/s; Car 2 was going 30 m/s before it stopped at the stop sign. There were no skid marks left by Car 2. The collision occurred at the stop sign, where Car 2 had stopped. After the collision, both cars were moving together in the same direction at 10 m/s before slowly rolling to a stop. You must now push Car 2, using 800 N of force, 10 meters off to the side of the road so no one else gets hurt.

Question:
What is the final momentum of the cars right after the accident?