1. 2009
    Dec
    14

    Bus Jump

    It’s finally time to analyze the latest Mythbusters episode again. This one has Grant, Tory, and Jessie testing another myth about that bus from the movie Speed. According to the Mythbusters, in the movie the bus, traveling at 70 miles per hour, was able to jump over a 50 foot gap in the highway, land safely, and continue on its way.

    There’s an obvious physics question in here: could the bus even make the jump? Well, while it’s in the air, the bus is basically just a projectile, and projectile motion is one of the most basic topics in physics. This shouldn’t be hard to calculate. The equation for uniformly accelerated motion in one dimension is

    $$x = x_0 + v_{0x} t + \frac{1}{2}a_x t^2$$

    In a two-dimensional system, like a flying bus (up and forward: two dimensions, assuming it doesn’t move sideways), we use two of these equations, one for each dimensions. And if we ignore icky things like air resistance, it’s easy to determine each of the individual factors in the equation:

    • Let’s choose coordinates such that \(x_0 = 0\) and \(y_0 = 0\), setting the edge of the road where …