2.4 Velocity vs. Time Graphs - Physics | OpenStax Strategy. The displacement is given by finding the area under the line in the velocity vs. time graph. The acceleration is given by finding the slope of the velocity graph. The instantaneous velocity can just be read off of the graph. To find the average velocity, recall that. v avg = Δ d Δ t = d f − d 0 t f − t 0.