Panic escape . Figure 2-16 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 `v_(s)=3.50m//s`, are each `d=0.25m` in depth, and are separated by `L=1.75m`. The arrangement in Fig. 2-16 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 5.0m ? (The answers reveal how quickly such a situation becomes dangerous. )

Answer

(a) 0.50 m/s; (b) 10 s