Spaceship 1 and Spaceship 2 have equal masses of 300 kg. They collide. Spaceship 1's final speed is 2 m/s, and Spaceship 2's final speed 1 m/s in the same direction. What is their combined momentum?
A. 600 kg-m/s
B. 900 kg-m/s
C. 1,200 kg-m/s
D. 3 m/s

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.