1. The problem statement, all variables and given/known data A 0.155-kg ball, moving in the positive direction at 13 m/s, is acted on by the impulse shown in the graph below. What is the ball's speed at 4.0 s? The graph is attached below. 2. Relevant equations J = F Δt 3. The attempt at a solution I thought that it might be zero because at 4 seconds the force is zero but now I look at it again and I'm thinking the equation might be 0 = 4-0 so the speed would be -4 but that doesn't make since.