1. The problem statement, all variables and given/known data Two particles have mass 0.12kg and 0.08kg respectively. They are intially at rest on a smooth horizontal table. Particle A is then given an impulse in the direction AB so that it moves with speed 3m/s directly towards B. Immediately after the particles collide the speed of A is 1.2m/s, its direction of motion being unchanged. (c) find the magnitude of the impulse exerted on A in the collision. 2. Relevant equations impulse = change in momentum (mv-mu) 3. The attempt at a solution (c) I get impulse = mv-mu = (0.12 x 1.2) - (0.12 x 3) = - 0.216 Ns But the mark scheme said the answer is + 0.216 Ns ... how can this be if the velocity after is less than the velocity before, i don't understand why??