Suppose a train traveling 90 mph takes four seconds to enter a tunnel. From there it takes one minute before the train is completely outside the tunnel. Find the length of both the train and the tunnel.

Answer 1

t = train length ... T = tunnel length

t = 90 mi/h * 5280 ft/mi * 4 s / 3600 s/hr

the train travels its length in 4 s
... it takes one minute (60 s) for the front of the train to traverse the tunnel

T = t (60 s / 4 s)