Answer:
Distance covered in 40 sec must be equal to length of train which is equal to 3520 feet.
Step-by-step explanation:
Speed of train = 60 mph = 88 feet/sec
Total time taken by front of train in travelling the tunnel = 40 sec
Length of train = s =?
Distance covered in 40 sec must be equal to length of train. So,
[tex]v=\frac{s}{t}\\\\s=v\times t\\\\s=88 \times 40\\\\s=3520 feet[/tex]