1. The problem statement, all variables and given/known data A police car joins a straight motorway at Juction 4 and travels for 12 km at a constant speed for 400 seconds, then it leaves at junction 5 and rejoins on the opposite side and travels for 8 km at a constant speed for 320 (s) to reach an accident. Calculate the displacement from junction 4 to the accident. 2. Relevant equations No idea, I really need explanation on how to work this out, a link and other practice questions would be really helpful. 3. The attempt at a solution I have not attempted it, but I know that with displacement graphs, deceleration is a downwards curve and acceleration is a curve with increasing gradient. When an object reverses its velocity changes, however I see no relevance of this to my question. Please HELP!