An object of mass 4 kg is initially at rest on a frictionless ice rink. It suddenly explodes into three pieces (I have no idea why it happened!). One chunk of mass 1 kg slides across the ice with a velocity 1.2 ms-1i and another chunk of mass 2kg slides across the ice with a velocity 0.8 m.s-1j. Determine the velocity of the third chunk in magnitude angle form.