From what height can you survive a dive into water?

Don't try this at home


Also in this week's column:

From what height can you survive a dive into water?

Asked by Jack Crompton of Liverpool, UK

The cliff divers of Acapulco amaze tourists with their bravery and skill. But from how much higher could they plunge without suffering serious injury or death?

Surprisingly, it is difficult to be precise as to this height limit. While some unlucky ones die of falls in their bathtub, others have survived falls from incredible heights. For example, The Free Fall Research Page lists the case of World War II Russian airman, Lt I M Chisov. Chisov's Ilyushin IL-4 bomber was shot down by German fighters in January, 1942. Chisov fell 22,000 feet (6,705 metres) and hit the edge of a snow-covered ravine and rolled to the bottom. Although badly injured, Chisov survived. Although this is not cliff diving into water, it shows what is possible.

Intricately involved in any such calculation of maximum survival height is terminal velocity. Terminal velocity is the maximum speed of free fall of a human in air. Once terminal velocity is reached, no matter how much higher one falls from, they will not increase their speed in falling. Although there is some dispute about this figure, the terminal velocity of a human is estimated to be about 325 km per hour.

The speed of a diver from a 30 metre cliff is estimated to be only about 90 km per hour. This is only one-third or so of the terminal velocity.

Another factor too is plunging position. If the diver is plunging head-first, their speed will be somewhat faster than if they were falling spread-eagled due to less drag in the head-first position.

According to Linn Emrich, author of The Complete Book of Sky Sports, first published back in 1970, a 77 kg (170 lb) person would reach terminal velocity after about 14 seconds. They would fall nearly 10,000 feet (3,048 meters) in one minute. Cliff divers are not in the air for anywhere near 14 seconds. This is why they can dive and survive.

Interesting facts

Some living creatures have a terminal velocity that is not fatal. For example, ants can survive falls from heights that would be easily fatal for humans. But cliff diving ants would not be nearly as popular with tourists in Acapulco.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney.

Liked this article? You can check out all The Odd Body columns here.


Other stories you might like

  • Meet Wizard Spider, the multimillion-dollar gang behind Conti, Ryuk malware
    Russia-linked crime-as-a-service crew is rich, professional – and investing in R&D

    Analysis Wizard Spider, the Russia-linked crew behind high-profile malware Conti, Ryuk and Trickbot, has grown over the past five years into a multimillion-dollar organization that has built a corporate-like operating model, a year-long study has found.

    In a technical report this week, the folks at Prodaft, which has been tracking the cybercrime gang since 2021, outlined its own findings on Wizard Spider, supplemented by info that leaked about the Conti operation in February after the crooks publicly sided with Russia during the illegal invasion of Ukraine.

    What Prodaft found was a gang sitting on assets worth hundreds of millions of dollars funneled from multiple sophisticated malware variants. Wizard Spider, we're told, runs as a business with a complex network of subgroups and teams that target specific types of software, and has associations with other well-known miscreants, including those behind REvil and Qbot (also known as Qakbot or Pinkslipbot).

    Continue reading
  • Supreme Court urged to halt 'unconstitutional' Texas content-no-moderation law
    Everyone's entitled to a viewpoint but what's your viewpoint on what exactly is and isn't a viewpoint?

    A coalition of advocacy groups on Tuesday asked the US Supreme Court to block Texas' social media law HB 20 after the US Fifth Circuit Court of Appeals last week lifted a preliminary injunction that had kept it from taking effect.

    The Lone Star State law, which forbids large social media platforms from moderating content that's "lawful-but-awful," as advocacy group the Center for Democracy and Technology puts it, was approved last September by Governor Greg Abbott (R). It was immediately challenged in court and the judge hearing the case imposed a preliminary injunction, preventing the legislation from being enforced, on the basis that the trade groups opposing it – NetChoice and CCIA – were likely to prevail.

    But that injunction was lifted on appeal. That case continues to be litigated, but thanks to the Fifth Circuit, HB 20 can be enforced even as its constitutionality remains in dispute, hence the coalition's application [PDF] this month to the Supreme Court.

    Continue reading
  • How these crooks backdoor online shops and siphon victims' credit card info
    FBI and co blow lid off latest PHP tampering scam

    The FBI and its friends have warned businesses of crooks scraping people's credit-card details from tampered payment pages on compromised websites.

    It's an age-old problem: someone breaks into your online store and alters the code so that as your customers enter their info, copies of their data is siphoned to fraudsters to exploit. The Feds this week have detailed one such effort that reared its head lately.

    As early as September 2020, we're told, miscreants compromised at least one American company's vulnerable website from three IP addresses: 80[.]249.207.19, 80[.]82.64.211 and 80[.]249.206.197. The intruders modified the web script TempOrders.php in an attempt to inject malicious code into the checkout.php page.

    Continue reading

Biting the hand that feeds IT © 1998–2022