A plane is sitting on a runway, awaiting takeoff. On an adjacent parallel runway, another plane lands and passes the stationary plane at a speed of 40 m/s. The arriving plane has a length of 40 m. By looking out the window (very narrow), a passenger on the stationary plane can see the moving plane. For how long a time is the moving plane visible?

This is a simple calculation involving speed, distance and time. What needs to be calculated is the time it takes for the plane to move through one point in space, and this can be calculated by using the information given in the question (the length of the plane is 40 m, and it is traveling at 40 m/s).

Calculation:

t(time) = d(distance) / s(speed)

t = (40 m) / (40 m/s)

t = 1 second

It would take one second for the plane to move through one point in space, from the tip of its nose to its tail. This calculation makes sense, because logically, if an object travelling at 1 m/s, passes a point in 1 second, logic would dictate that the object is 1 m in length. The same principle applies to this question.