The superhero’s love interest (or perhaps an innocent bystander) dangles from a tall building (or helicopter). The music speeds up. The grip loosens. Then, with a scream, the victim falls, and it is up to the superhero to catch them.
Superman & Lois Lane, IGN.com
Movies have gotten better about allowing for some deceleration in the [almost] inevitable catch, but we’ve been using a scene from Marissa Meyer’s Renegades as a case study for looking at the physics of a long fall and a last-second catch. In that scene, Captain Chromium (invincible, unusually strong) casually catches Thunderbird (flies, throws lightning, recently netted by a villain) after a fall of “hundreds of feet.”
In the first post we discovered that a fall of 300 feet would leave Thunderbird going about 95 MPH when Captain Chromium caught her.
In the second post we looked at terminal velocities and wind resistance and found that if Thunderbird was tumbling non-aerodynamically in a net, she might have been going as slow as 81 MPH when Captain Chromium caught her.
Today we look at how much force Captain Chromium’s metal-reinforced arms must have applied to Thunderbird’s tumbling body.
Newton’s Second Law of Motion saves the day on this one. That law says that (for a constant mass), force equals mass times acceleration. To find the force on Captain Chromium’s arms, we just need to know Thunderbird’s mass and acceleration.
110 g’s is a lot. Normal humans can only survive about 9 g’s according to Scientific American. Standing on the surface of the sun would only subject you to 28 g’s (though you’d also have other temperature-related problems as well).
But back to our original question – how much force does this deceleration put on Captain Chromium’s arms (and Thunderbird’s body)?
If force is mass times acceleration, our force is 61.7 kg * 1075 m/s2 = 66,328 N. Putting that in units most of us understand, Captain Chromium’s catch requires 14,911 pounds (applied constantly over a distance of two feet).
That’s a lot. Captain Chromium is feeling the weight of two Ford F250s and seven NFL players combined. Conversely, Thunderbird is feeling the weight of fully-occupied F250 applied through each of the captains Chromium-reinforced hands.
Without getting too morbid, I think it’s safe to say that Thunderbird would not be walking away from this catch feeling 100%.
Thanks for reading! Connect with me on social media to get updated when I post a new blog topic.
In the first post we discovered that a fall of 300 feet would leave Thunderbird going about 95 MPH when Captain Chromium caught her.
In the second post we looked at terminal velocities and wind resistance and found that if Thunderbird was tumbling non-aerodynamically in a net, she might have been going as slow as 81 MPH when Captain Chromium caught her.
Today we look at how much force Captain Chromium’s metal-reinforced arms must have applied to Thunderbird’s tumbling body.
Newton’s Second Law of Motion saves the day on this one. That law says that (for a constant mass), force equals mass times acceleration. To find the force on Captain Chromium’s arms, we just need to know Thunderbird’s mass and acceleration.
- Thunderbird’s Mass: According to Medical News Today, the average weight for a woman in North America is 177lbs. This may be skewed high, since the same source says 74% of North American women are “overweight,” and Thunderbird’s description in the books does not indicate that she is overweight. A better metric might be the world-wide average weight for women (136lb). Converting to metric mass, this means Thunderbird’s mass is 61.7 kg.
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Thunderbird’s Acceleration: This one takes some figuring:
- Thunderbird lands in Captain Chromium’s “waiting arms.” If he starts catching Thunderbird at eye-level and finishes the catch at waist level, he decelerates her over a distance of two feet.
- Since Thunderbird starts at 81 MPH and ends at 0 MPH, her average speed over that two feet (assuming constant acceleration) is 40.5 MPH.
- Traveling at 40.5 MPH, two feet takes 33.67 milliseconds.
- Thunderbird’s acceleration, therefore, is 81 MPH per 33.67 milliseconds. Converting that to SI units, Thunderbird’s acceleration is 1075 m/s2, or 110 g’s.
110 g’s is a lot. Normal humans can only survive about 9 g’s according to Scientific American. Standing on the surface of the sun would only subject you to 28 g’s (though you’d also have other temperature-related problems as well).
But back to our original question – how much force does this deceleration put on Captain Chromium’s arms (and Thunderbird’s body)?
If force is mass times acceleration, our force is 61.7 kg * 1075 m/s2 = 66,328 N. Putting that in units most of us understand, Captain Chromium’s catch requires 14,911 pounds (applied constantly over a distance of two feet).
That’s a lot. Captain Chromium is feeling the weight of two Ford F250s and seven NFL players combined. Conversely, Thunderbird is feeling the weight of fully-occupied F250 applied through each of the captains Chromium-reinforced hands.
Without getting too morbid, I think it’s safe to say that Thunderbird would not be walking away from this catch feeling 100%.
Thanks for reading! Connect with me on social media to get updated when I post a new blog topic.