Before Taking off, a plane travels at a speed of 1/4 miles per second, The runway is 5 miles long, How many seconds, does it take for the plane to get to the end of the runway?

Answer 1

1/4 mi per second is 4 seconds per mile
So, that would make 20 seconds to go 5 miles

But of course, the plane does not go at take-off speed the whole way down the runway, right?