To solve the problem you must first know that by keeping the linear moment P1 = P2. You must find P1 from the system and equal it to P2 of the system, from that equation you clear the final velocity 1. Which will result in V1f = 60.16 cm / s to the north.I attach the solution.
The compass magnet aligns itself with the earths magnetic field.
I believe is A) Inner core
Answer:
static electricity and then lightning rod