Two rolling golf balls of the same mass collide. The velocity of one ball is initially 2.7m/s (E). After the collision, the velocities of the balls are 2.49m/s(62.8 N of W) and 2.37m/s (69.2 S of E). What is the initial velocity of the second ball? So i know that the masses are the same, and the initial velociy of the 1st ball. Hence by using the conservation of momentum formula, I get v_2= (V_1+V_2)v1 (here, the capital V's r the final velocities and the small v's are the initial velocities) So now if it was one dimension, it straight forward. But since this is 2-dimensional, its confusing. I know we have to draw somthing like a vector diagram. So, i tried doing that. I tried attaching the file but I can't seem to do it. So, i'll try to explain the my diagram in words! So one ball is moving in the north west direction, the other in the south east. I drew a line frm the centre of the 1st ball going NW. Thats V_1. With that line as the hypotunese, i drew V_1x and V_1y. And the angle betwee V_1y and V_1 is 62.8 degrees. SO i used cos and sine to figure out V_1x and V_1y. I did the same thing for the 2nd ball..This is all i could do...Any help..