# How Long Would It Take for a 747 to Stop, Like in ‘Tenet’?

This acceleration is for any change in velocity. It does not matter whether the object is increasing or decreasing in speed – it is still an acceleration. If you know the acceleration for something, you can find the stopping distance using the following kinetic equation (Here is a derivation if you want it).

In this expression, V1 Is the initial velocity (20 mph in this calculation) and V2 The final velocity will be – hopefully it will stop. So, the stopping distance (wouldx) with a known acceleration would be:

Now all I need to do is get a value for the acceleration of a Boeing 747. Ah ha! it’s not that easy. Certainly, large aircraft stop all the time – this is usually called “landing”. However, the normal method will not work here during landing. Usually a plane like the Boeing 747 will use two things to slow down. It not only uses wheels that have brakes, but also has reverse thrusters. Reverse thrusters are essentially forces from the engines directed backwards (thus the “reverse” part). This rearward thrust force, along with the brake, slows the aircraft.

For this stunt theoryThe 747 will only have brakes as it is not a fully functioning aircraft. So, what acceleration will happen if an aircraft does not use reverse thrusters? Well, we are in luck. Here this thing is called rejected test (RTO). For this maneuver, an aircraft starts and gets up to overcome the momentum. At that point, the pilot slams on his brakes (no reverse thrusters) and comes to a stop. This is a worst-case test to ensure that aircraft brakes can handle extreme cases.

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