To drive or not to drive

V and R sit down to discuss scientifically sound driving decisions.R found himself perplexed today when he thought he could easily cross an intersection but the car before him came to a sudden halt. We use this alarming situation to discuss the science behind some driving etiquettes.When is it better to stop at and when to drive through an intersection? And should you swerve around or brake hard to avoid ramming into a vehicle that came to a sudden halt in front of you?