by David Colarusso - March 20th, 2007
In the movie Speed a bus is forced to jump an unfinished portion of highway to avoid setting off a bomb on the bus rigged to explode should it go below fifty miles an hour. Of course, they make it, but we want to know if this could really happen.
The Tabletop Explainer
Episode Five (5)
Could that actually happen?
Phylm examines the bus jump from Speed
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In the movie Speed a bus is forced to jump an unfinished portion of highway to avoid setting off a bomb on the bus. This bomb is rigged to explode if the bus goes below fifty miles an hour.
[clip of jump]
Of course, they make it, but we want to know if this could really happen.
First it’s important to understand how projectiles fly through the air. All objects, regardless of their mass, fall at the same rate in a vacuum. [Apollo 15 video clip] Additionally, an object’s time falling is independent of its horizontal velocity. So no matter how fast the bus is traveling, should it launch horizontally, it will always fall some amount and fail to make it.
So for the bus to make the jump, it must launch at some angle. Now this is a little bit of a cheat as I should explain more. However, there is an equation in mechanics know as the range equation which relates the initial velocity of a projectile to the distance it covers horizontally. If we examine the movie, we can find the speed the bus is traveling and the distance it is meant to cover. “g” is the acceleration due to gravity which we know. So we can check to see how much of an incline we need for a lunch something that will just make it.
We simply rearrange the equation, solving for the launch angle. Plug in our values, and presto. We get approximately five degrees. That’s not much of an angle. Now there’s no clear shot of the highway. So it’s hard to say if there’s actually an incline, but it seems possible there could be.
Oddly, the bus seems to jump upwards at the last moment, an artifact of Hollywood tinkering, but it does seems we’ve cleared one hurtle. If we really believe the bus left the road going 68 miles and hour, and the jump adjusted for the length of the bus was a mere 50 feet, as long as there was a 5 degree incline, it seems possible the bus could have made the jump.
However, a quick glimpse at the Speed DVD’s special features makes it clear the landing would most likely wreck the bus. Not to mention, we haven’t thought about wind resistance or the bus’s rotation. Nonetheless, it’s not entirely absurd.
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