A pickup truck moving at 28 m/s must come to a stop in a distance of 191 meters to avoid hitting a boulder that has fallen onto the road. How much time does the driver have to avoid an accident?

Use the kinematic equation

Δx=½(v

_{i}+v_{f})t with v_{i}=28 m/s, v_{f}=0, and Δx=191 m,and solve for t.