Question

A body at rest explodes into three equal parts, two parts after explosion fly off due north and west respectively with velocity 8m/s then calculate the magnitude and direction of velocity of 3rd pat.

Answer 1

since each part has the same mass, conserving momentum is just conserving velocity:

<0,8> + <-8,0> + <x,y> = 0

or, since the resultant momentum of the two known parts is NW, the 3rd part must go SE.