Tom Hanks character, Robert Langdon, hero of Dan Brown’s Angels and Demons (2009) jumps from a helicopter and falls thousands of feet into Rome’s Tiber River and survives, of course.
Ahhhh! Look up. It’s raining Tom Hanks!!!!!
There are three factors we must consider, mathspigs, when jumping or diving from a great height:
1. Surface Impact
3. How long you can hold your breath.
We’ll start with water surface impact. According to the Free Fall website falling into water is not a good survival strategy. http://www.greenharbor.com/fffolder/questions.html#anchor1234566 ‘Someone falling without a parachute from more than 2,000 feet or so would be falling quite a bit faster than 100 miles per hour (161 kph) …………The folks who have survived falls into water have had streaming parachutes above them, which probably slowed their falls to the 60-mph range (97 kph). Having a streaming parachute helps in another way because it aligns the body in a position where the feet enter the water first.’
The website goes on to explain that water is an INCOMPRESSIBLE FLUID. It’s like landing on concrete. Landing in mud, on snow, on trees, on circus tents etc helps break the fall. Moreover, jumping off a bridge into turbulent sea may be safer than jumping into calm water.
The next issue is, if you are going to dive or jump into water and, miraculously survive the impact, how deep should the water be?
Sports Smart Canada (Visual Expert Website: http://www.visualexpert.com/Resources/divingaccidents.html ) recommend that the water depth should be twice the height of the dive. Olympic divers often practise their dives in a bubble pool (like a spa). This reduces the impact for a bad dive but the water must be much deeper. So a water depth of double the height of the drop is realistic if, say, you are jumping or diving from the top of a waterfall into aerated water. You can work out appropriate depths if you were diving into water from heights such as:
Eiffel Tower: 300m
Note: You would need a big swimming pool!!!!
Sydney Harbour Bridge Clearance: 52.4 m
Brooklyn Bridge NY Clearance Above Water: 41m
10 m Tower/ 4th Story Window:
Statue of Liberty Height: 93 m
Note: Assume you’re diving into water from ,say, a helicopter as in the Demons & Angels movie.
Assuming you survive the impact of the jump and the water is deep enough, would you survive the journey down and then the swim to the surface on one breath???????
William Trubridge broke the world record in Unassisted Freediving with a dive to 88m (288ft) in 3 minutes 30 seconds on 2nd May 2009 which you can view on Youtube