Monday, March 31, 2014

a rant about how movies are never accurate to physics

I recently saw a movie in which a character was thrown at a moving freight train and somehow survived. I was thinking "That can't be right. Freight trains are heavy. Really heavy. And they move fast!"

So I googled the average speed of a freight train, since wolfram|alpha just wanted to compare the movie statistics for a movie called cargo, the train, and speed. So, I found the rail speed limits for the united states and assumed it would be close, about 59 MPH.

I looked up the weight of freight trains next, which was about 250 thousand pounds. So, convert that to kilos(Since pounds are a measurement of gravitational force, not mass), and it comes out as about 113 thousand kilos.

So 59 MPH is about 94 thousand meters per second. Now, if we use simple high school math:

113000kg * 94000m/s = 10622000000N

This is the tensile strength of bone: 52000000N/m².(at least for cortical bone, which make up 80% of bone.)

The guy in this move was thrown into the train face first. I think he should've died, and by the amazing powers of plot device, he didn't.

Movies are never accurate to physics. I will never know why.

If I ever make a movie, I'm hiring a physics consultant and forcing directors to listen to him.

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