4. (20 marks) A bomb of 3.0 kg sliding on a frictionless ice surface explodes into two fragments: the first fragment of 1.0 kg travels north at 15 m/s and the second fragment travels east at 12 m/s. (a) (10 marks) What is the original speed of the bomb? (b) (5 marks) Consider the reverse of the explosion, i.e., the aforementioned two fragments traveling at the their reverse velocities collide into each other. Show that if the two fragments are stuck together after the collision, the resulting 3.0 kg object moves at the same speed as your answer in part (a). (c) (5 marks) is the collision described in (b) elastic or inelastic?