Explosion of particles

[Clutch306]

A suspicious package is sliding on a frictionless surface when it explodes into three pieces of equal masses and with the velocities:
(1) 7.0 m/s, north;
(2) 4.0 m/s 30 degrees south of west;
(3) 4.0 m/s 30 degrees south of east.

(a)What is the velocity(both magnitude & direction) of the package before it explodes?
(b) What is the displacement (both magnitude & direction) of the center of mass of the three-piece system (with respect to the point the explosion occurs) 3.0s after the explosion?

[arildno]

1. What do we mean by Center of Mass?
2. How is Newton's laws formulated for C.M?
In particular, what is meant by the terms external and internal forces, and how can you use the fact that the forces associated with the explosion are to be considered internal forces?

[sunilkamadolli]

another Hint: Use law of Conservation of Linear Momentum...

use vector equations and remember since therez no external forces the linear momentum component along an axis cannot change.