1. The problem statement, all variables and given/known data Problem: A person wearing a seatbelt can withstand an acceleration of -0.030 m/s2. How thick should barriers be to safely stop a car that hits a barrier at 110 km/h? 2. Relevant equations F=m*a? 3. The attempt at a solution I so far have no attempt. I do not know what sort of formula can be used or what type of problem it is ie. constant velocity, displacement, friction so on. The sort of help that I need is a possible formula you might know of or even what kind of problem this is.