Subwoofer in my car plays music but doesn't move or have any bass sound?

[koutetsu12]

My dad bought a used car and it had a subwoofer in the back, I've been trying to get it to work. When I play music, I can hear the music through the subwoofer, but it does not move at all and doesn't have any bass sound at all. I tried touching the 2 wires to a 9v battery and it moves in and out but not when playing music. Any help appreciated, thanks