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How rollercoasters affect your body - Brian D. Avery - Video học tiếng Anh
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How rollercoasters affect your body - Brian D. Avery
How rollercoasters affect your body - Brian D. Avery
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0:06
In the summer of 1895, crowds flooded the Coney Island boardwalk
0:12
to see the latest marvel of roller coaster technology:
0:16
the Flip Flap Railway.
0:18
This was America’s first-ever looping coaster
0:21
– but its thrilling flip came at a price.
0:24
The ride caused numerous cases of severe whiplash,
0:28
neck injury and even ejections,
0:31
all due to its signature loop.
0:33
Today, coasters can pull off far more exciting tricks,
0:37
without resorting to the “thrill” of a hospital visit.
0:40
But what exactly are roller coasters doing to your body,
0:44
and how have they managed to get scarier and safer at the same time?
0:48
At the center of every roller coaster design is gravity.
0:53
Unlike cars or transit trains,
0:55
most coasters are propelled around their tracks
0:58
almost entirely by gravitational energy.
1:01
After the coaster crests the initial lift hill,
1:04
it begins an expertly engineered cycle –
1:08
building potential energy on ascents and expending kinetic energy on descents.
1:13
This rhythm repeats throughout the ride,
1:16
acting out the coaster engineer’s choreographed dance
1:19
of gravitational energy.
1:21
But there’s a key variable in this cycle that wasn’t always so carefully considered:
1:26
you.
1:27
In the days of the Flip-Flap,
1:29
ride designers were most concerned with coasters getting stuck
1:32
somewhere along the track.
1:34
This led early builders to overcompensate,
1:36
hurling trains down hills
1:38
and pulling on the brakes when they reached the station.
1:41
But as gravity affects the cars, it also affects the passengers.
1:45
And under the intense conditions of a coaster,
1:48
gravity’s effects are multiplied.
1:50
There’s a common unit used by jet pilots,
1:53
astronauts,
1:53
and coaster designers called “g force”.
1:57
One G force is the familiar tug of gravity you feel when standing on Earth
2:01
– this is the force of Earth’s gravitational pull on our bodies.
2:05
But as riders accelerate and decelerate,
2:08
they experience more or less gravitational force.
2:12
Modern ride designers know that the body can handle up to roughly 5 Gs,
2:17
but the Flip-Flap and its contemporaries routinely reached up to 12 Gs.
2:22
At those levels of gravitational pressure,
2:24
blood is sent flying from your brain to your feet,
2:27
leading to light-headedness or blackouts
2:30
as the brain struggles to stay conscious.
2:32
And oxygen deprivation in the retinal cells impairs their ability to process light,
2:38
causing greyed out vision or temporary blindness.
2:41
If the riders are upside down, blood can flood the skull,
2:45
causing a bout of crimson vision called a “redout”.
2:49
Conversely, negative G’s create weightlessness.
2:53
Within the body,
2:54
short-term weightlessness is mostly harmless.
2:57
It can contribute to a rider’s motion sickness
2:59
by suspending the fluid in their inner ears
3:02
which coordinates balance.
3:03
But the bigger potential danger
3:05
– and thrill –
3:06
comes from what ride designers call airtime.
3:09
This is when riders typically experience seat separation,
3:13
and, without the proper precautions,
3:14
ejection.
3:15
The numerous belts and harnesses of modern coasters
3:18
have largely solved this issue,
3:20
but the passenger’s ever-changing position can make it difficult
3:24
to determine what needs to be strapped down.
3:26
Fortunately, modern ride designers are well aware
3:29
of what your body, and the coaster,
3:31
can handle.
3:32
Coaster engineers play these competing forces against each other,
3:36
to relieve periods of intense pressure with periods of no pressure at all.
3:40
And since a quick transition from positive to negative G-force
3:43
can result in whiplash, headaches, and back and neck pain,
3:47
they avoid the extreme changes in speed and direction
3:50
so common in thrill rides of old.
3:53
Modern rides are also much sturdier,
3:56
closely considering the amount of gravity they need to withstand.
3:59
At 5 G’s, your body feels 5 times heavier;
4:03
so if you weigh 100lbs,
4:04
you’d exert the weight of 500 lbs on the coaster.
4:08
Engineers have to account for the multiplied weight
4:11
of every passenger when designing a coaster’s supports.
4:15
Still, these rides aren’t for everyone.
4:17
The floods of adrenaline, light-headedness, and motion sickness
4:21
aren’t going anywhere soon.
4:23
But today’s redundant restraints, 3D modeling and simulation software
4:28
have made roller coasters safer and more thrilling than ever.
4:32
Our precise knowledge about the limits of the human body
4:34
have helped us build coasters that are faster, taller, and loopier
4:38
– and all without going off the rails.
