1) An artillery shell of total mass 18 kg is at rest when it explodes into three pieces, each of mass 6 kg. Two of the pieces fly off at 10 m/s at right angles to each other. What speed does the third piece have in m/s?
2) Two identical carts are on an air track. the first cart slides in at a velocity of +10 m/s and hits the second, which is originally at rest. If the velocity of the second cart after the collision is +5 m/s, what is the velocity (in m/s) of the first cart after the collision?