The problem that gripped students this week was this:
A car traveling at 20 m/s slows to a stop in 50 m. A 70 kg passenger rides with out a seat belt. The coefficients of static and kinetic friction between the seat and the passenger are equal to 0.3 and 0.2, respectively.
Does the passenger slide in his seat? If so, how does the passenger’s acceleration compare to the car’s acceleration?