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» Explaining Inception: an FAQ Guide
After the van drove off the bridge, it wouldn't last more than 3 seconds in this level before hitting the water. How could Arthur put the bombs in 1 min? (20 times) I mean the it is definitely more than 1 min in the movie.
From the scene in the movie when Yusef first drives the van off the bridge, the bridge looks about 300 feet tall (roughly the length of a football field, maybe a bit more). Knowing this much, we can use a kinematic equation to find out how much time Arthur really has in his 20 times dilated dream world.
We have acceleration of roughly 10 meters per second squared due to gravity, we have initial vertical velocity to be 0 m/s, we have the height of the bridge (roughly 100 meters), and we're looking for time before impact.
Using the equation d=Vit+(1/2)(a)(t squared) and plugging in the different variables, we get t-squared=20, and t equals to 4.5 roughly. However there's still the matter of 2 things:
1, from the moment the "kick" happens (the back of the van hitting the rail) to when the van is in actual free fall, there is a period of time in between. Let's say it takes 1 second for the van's front wheels to become completely suspended in midair and freefall begins;
2, air resistance is very significant on an object as big as the van. The kinematic equation assumes it to be a vacuum condition and that the gravitational pull is unaffected by drag force, however in the real world the large surface area of the van will induce an immense amount of drag force that decreases the acceleration due to gravity. (The principle behind parachutes) So taking this into consideration it will add at least a second or two to the overall time.
However let's be lenient here and say that there is no drag force. And that from the moment the van hit the rail to the moment it hits the water there is a 5.5 second differential. Which translates to 110 seconds in arthur's world, or roughly 2 minutes, which is plenty time for him to gather everyone together (30 seconds), push them to the elevator which is right outside (30 seconds), get through the top of the elevator, snap the string (20 seconds), float to the bottom, plant the charges, get back inside (30 seconds), and do his little count down.
All this without taken into consideration the large drag force the van experiences.
It's all physics, my friend!