Basic motion concepts can be difficult to understand for some students. Following is a video from People's Physics Book by James Dann:
Here is a simulation we made, in just a few minutes, to simulate this scenario:
The simulation allows students to engage with the concepts in a hands on manner. They can click the "Charts" button at the bottom left to see how the velocity, acceleration and other variables change with time. Students can also see the numbers updating as the simulation progresses. First click on the arrow icon at the top and select one of the cars. Then click on the "Data" button at the bottom left. Finally, the "Settings" button allows control of which signals are charted, copy/paste access to chart data and even comparison with analytical expressions to check the accuracy of simulation results.
Its important to note that creating and publishing this simulation to this blog took only a couple of minutes. It was done in the web-browser without any software download or installation. Just login to www.siminsights.com and start creating and sharing your simulations.