Two physics enthusiasts devise an experiment in which a 40-centimeter-long thread suspends a bar magnet(m = 10g). When another bar magnet is brought close to the first one with the identical poles facing each other (north to north or south to south),  they repel one another. If the second magnet is held in place it causes the hanging magnet to swing out to a 15-degree angle and remain there. Determine the magnitude of the magnetic force that causes the repulsion between magnets (making it swing).