Can you solve the MAGNET RIDDLE? ft YouTube CEO Susan Wojcicki

1: produce iron particles with the file and put them around the iron bars. You will get to see the structure of the magnetic field only around the magnetic one.
2: put the string around the two iron bars and test each one, if it aligns with the magnetic field of the earth if you let it alone and undisturbed for long enough. The one that aligns is magnetic, if the magnetic field goes along the length of the iron bar.
3 (mostly hypothetical): hitting them with the hammer, the hits may strengthen the pull between the two bars in case of the non-magnetic bar and don't change at all or weaken it in case of the magnetic iron bar since the magnetic domains get a nudge with each hit and may align with the external magnetic field of the earth in case of the non-magnetic bar while those hits may change and disturb the alignment of magnetic domains in the already magnetised bar.