1. The problem statement, all variables and given/known data a tinnes ball of mass 150 gm moves with velocity 11.2 m/s to collide with a racket , after collision it is rebounded with vilocity 7 m/s ...find :-the impulse of the racket on the ball. 2. Relevant equations I = m (delta) v what i want to know .. is when do we use the vilocity with the negative direction ?? i mean when we answer it can we calculate 0.15 * ( 11.2-7)= 0.63 kg.m/s or 0.15* (11.2-(-7))=2.73 kg.m/s so what is the right answer ???!