1. The problem statement, all variables and given/known data A 64kg student is standing in the middle of a frozen pond with a frictionless surface while carrying 2 books, a physics book with a mass of 2.5kg and a biology book with a mass of 3.5kg. The physics book is thrown with a speed of 6m/s relative to the student to the right and then the biology book is thrown in the opposite direction with a speed of 4m/s relative to the student. Calculate the velocity of the student after the biology textbook is thrown. 2. Relevant equations E = 1/2 mv(squared), initial moment = final momentum, therefore mv (initial) = mv (final), maybe more, im not sure 3. The attempt at a solution Since the student is at rest, the initial momentum is obvisiously 0. But once the first book is thrown and then the second book, i don't know how to calculate the velocity of the student after each time a book is thrown.