Rocket man and the perils of acceleration
Stories from Physics for 11-14 14-16
The highest empirically recorded acceleration survived by a human was experienced by the test pilot John Stapp while strapped to a rocket sled that could produce just under 180 kN of thrust. He experienced a peak acceleration of 42.6 g and one second of acceleration at 25 g. In five seconds, he reached 1020 km/hr and was then decelerated in just 1.4 seconds. He suffered temporary blindness from burst blood vessels in his eyes, cracked ribs, broken wrists and damage to his circulatory and respiratory systems.
A paper analysing survival rates from falls reports the case of a woman who fell six storeys, and though it is estimated she experienced a deceleration of 140g, she suffered no significant injuries. The sudden jolt caused by opening a parachute can lead to decelerations between 9
|6.3 g||Tower of Terror, Gold Reef City, Johannesburg, South Africa|
|5.9 g||Shockwave, Six Flags over Texas, Arlington, Texas|
|5.5 g||Detonator, Thorpe Park, Surrey, UK|
Though humans struggle to tolerate high accelerations, researchers in Japan have discovered bacteria can be successfully cultivated in an ultracentrifuge at accelerations over 400,000 g. Carnivorous aquatic bladderworts use a suction trap mechanism to capture prey; the fluid accelerated by the mechanism can reach a peak acceleration of 600 g. However, this acceleration is dwarfed by the abilities of fungi that live on herbivore dung. Ascomycota and zygomycota use fluid-filled stalks, like squirt guns, to accelerate spores up to 180,000 g. In the animal world, mantis shrimp appendages have been recorded as reaching accelerations of up to 104,000 m/s 2.