1. The problem statement, all variables and given/known data A football player (90 kg) moving east collides with another football player (80 kg) moving north. When both players collide, a helmet (2 kg) is ejected south at a velocity of 5 m/s. If both players fall to the ground and slide a distance of 2 m North-East with a friction coefficient of 0.6, What was the velocity of both football players upon collision? 2. Relevant equations I'm assuming this requires the Kinetic Energy and the Work Energy Theorem. W = K Wf = Kf - Ki Wf = 0 - Ki 3. The attempt at a solution I have absolutely no idea how to solve this problem. Every single collision example in the class manual or anywhere online for that matter has more data in the problem statement. Either the initial velocity is given for both football players and/or there is orientation angle given to the sliding distance with the friction coefficient. It would be much appreciated if somebody could point in the right direction to solve this problem. Tutorials or similiar examples would also be great. Thank you.