13. A bomb initially at rest on a smooth, horizontal surface is exploded into three pieces. Two pieces fly off horizontally at a 60° angle to each other, a 2.0

kg piece at 20 m/s and a 3.0 kg pieceat 12 m/s. The third piece flies off horizontally at 30 m/s. a. Determine the direction of motion of the third piece. b. What is its mass?