A 4.0-kg mass has a velocity of 4.0 m/s, east when it explodes into two 2.0-kg masses. After the explosion one of the masses has a velocity of 3.0 m/s at an angle of 60° north of east. What is the magnitude of the velocity of the other mass after the explosion?
◦ 7.9 m/s
◦ 8.9 m/s
◦ 7.0 m/s
◦ 6.1 m/s
◦ 6.7 m/s