# physics

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The figure below 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 = 4.1 m/s, are each d = 0.30 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 the layer of people at the door increase?

(b) At what time does the layer's depth reach 4.1 m?

• physics -

a person gets to the door each 1.75/4.1 seconds. So depth increases .3m each time.

rate=.3/(1.75/4.1) m/s

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