# General situation in which a stream of people attempt

The figure shows a general situation in which a stream of people attempt to escape through an exit door that turns out to be locked. The people move toward the door at speed vs =3.50 m/s, are each d =0.25 m in depth, and are separated by L =1.75 m. The arrangement in the figure occurs at time t =0. (a) At what average rate does the layer of people at the door increase? (b) At what time does the layer’s depth reach 5.0 m?