Two objects, A and B, both with a mass of 2 kg, collide. The velocities before the collision are ViA =15i + 30j m/s, (3) ViB = - 10i + 5j m/s, (4) After the collision, object A has a final velocity VJA = -5i + 20j m/s. (5) What is (a) the final velocity of B? , and (b) the change in the total kinetic energy of the system (including sign)?