Post created by Amanda
If you have ever seen Iron Man 3, you probably remember the scene where he saves thirteen people that had been sucked out of an airplane. And while watching the heroic actions you might be awed at how he was able to successfully catch all thirteen before they hit the water below, after closely examining the physics behind it you’ll realize it is a bit inaccurate. When Iron Man caught the first victim, Heather, she had already been falling for quite some time.
And while it’s hard to know exactly how fast Heather was falling in the movie, the article How Big a Fall Can a Person Survive? provides a pretty good estimate: “A free-falling 120lb woman would have a terminal velocity of about 38m per second...and she would achieve 95% of this speed in about seven seconds. That equates to a fall of around 167m, which is near 55 stories high.” Though the movie doesn't clearly state how long Heather had been falling, it is accurate to assume it had been more than seven seconds, meaning she had reached at least 95% of her terminal velocity, or the largest velocity that can be reached by something in free fall (How Terminal Velocity and Free Fall Work). At terminal velocity, the velocity is constant at its highest speed, and as we have learned in class, acceleration is equal to change in velocity divided by change in time, or a=△V/△T. Since Heather’s velocity is no longer changing, she will have zero acceleration. But though she is no longer speeding up as she falls, she is still falling very quickly, and at this speed any sudden stop would surely kill her… which includes stopping when Iron Man caught her. So while Iron Man’s actions that day may have seemed heroic, in reality he only made her inevitable death occur a little bit earlier than expected.
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