Physics: More Useful than Calculus

There were two subjects I loathed in high school, two paths of academic pursuit that I was dragged down only by the belief that my college applications would look weak without them: Physics and Calculus. And I kind of thought that once I got into the college of my choice I could just erase the nightmares of trying to understand X approaching the limit of Y.

But as my friend (with a car) and I were pulling the old maps, ice scraper, and CDs out of my crumpled car in the tow lot I got my first daylight look at the other two cars involved in my accident. The first SUV that caused the rear-ending chain reaction accident was entirely smashed in front, with the driver's airbag deployed. My car, on the end of the chain...well, you've seen it. But the SUV in the middle, the one that was hit and then smashed me, looked like it hadn't even been in the same accident. The back bumper was damaged, and the front bumper was broken... but it was really minimal.

My friend and I marveled at this. Was it because the Jeep SUV was just so massive and sturdy? Or... was it Physics?

So I consulted the same person that I would have asked if we were in high school study hall. James explains it as follows:

You know those desk toys with the clicky silver balls? You know how you lift a ball at one end and drop it so it swings into the stationary balls and then the last ball on the chain flies up? Well, sadly, that's basically what happened to you. As for the ball (or SUV) in the middle of the chain there are 2 pertinent properties that effect what happens to it and you. The first is how rigid it is. In the desktop toy the balls are very solid, which means they transfer force very efficiently (those bastards). You can imagine that if you replaced one of the middle balls with a very soft, foam ball, it would collapse when hit and the ball at the end would barely move.

The second thing to consider is how freely the balls can move. Imagine if you nailed one of the middle balls in place so it couldn't swing at all. Again, the ball at the end would barely move (this one's a bit harder to imagine because in the desk toy the middle balls don't appear to move, but trust me, if you nailed one down the ball at the end wouldn't move).

So with that in mind, we can figure out what happened to you. We know that SUVs are rigid, so that just leaves the question of brakes. Sadly it looks like the SUV had the brakes only partially applied at the time of impact (or the brakes weren't strong enough). If the driver had their foot firmly on the pedal and the emergency break applied then you would have been spared from most of the impact (and the SUV would have taken more of the impact).

Or to directly answer your question, yes, most of the force was transferred through the SUV and into your poor car. This is partially due to the middle car being the strongest and partially due to it being able to move (relatively) freely.


Turns out Physics has real-life applications, unfortunately pertinent in an unhappy way. At least Calculus has not come back to haunt me. Unless calculating how leasing a car works will be more complicated than I can imagine. (I'll hopefully know tomorrow whether the insurance company is totalling my car.)

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