Three bullets are fired simultaneously by three guns aimed toward the center of a circle where they mash into a stationary lump.
The angle between the guns is 120°. Two of the bullets have a mass of 3.90 x 10⁻³ kg and are fired with a speed of 368 m/s. The third bullet is fired with a speed of 618 m/s and we wish to determine the mass of this bullet.