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Gasoline has approximately 56 megajoules of chemical energy per liter,
每升汽油含有约五千六百万焦耳的能量，
which is more energy than you get from exploding the same of amount of TNT, and is enough to power a toaster for a full day.
这比引爆等量TNT所释放的能量还多，足以使一台烤面包机工作一整天。
Cars work by burning gasoline to convert that chemical energy into the kinetic energy of motion of the car,
汽车通过燃烧汽油工作，在此过程中，汽油的化学能转化为汽车的动能，
though almost 80% of it is lost as heat in the engine.
尽管80%的热量都在发动机散热中流失。
Still, 20% of 56 million joules is a lot of joules…
尽管如此，5600万焦耳的20%是很多焦…
To give a direct sense of gas-to-car conversion,
直观一点说明汽油到车的能量转换，
it takes about five teaspoons of gas to accelerate a 2 ton car to 60kph,
要把一辆两吨的车加速到60千米每小时需要约五茶匙的汽油，
and about a third of a cup more for every additional minute you want to keep it going at that speed.
每保持这个速度行进一分钟，就需要再加约三分之一杯汽油。
That might not sound like a lot of fuel,
这也许听起来需要的汽油并不多，
but the energy of a car moving 60kph is equivalent to dropping an elephant–or stegosaurus–from the top of a three-story building.
但以每小时60千米运动的汽车的动能，约等于一头大象或者剑龙从三层楼掉下去时的能量。
And in order for the car to stop, all that energy has to go somewhere.
车要停下来的时候，这些能量必须得有个去处。
If the brakes do the stopping, they dissipate the energy by heating up.
如果是用刹车片把车停下来，那就是通过升温来释放这些能量。
Or in the case of a collision, energy is dissipated by the bending and crumpling of metal in the outer areas of the car.
如果是撞车停下的情况，这些能量就会通过车辆外围金属的扭曲形变释放。
And just like how smooth braking is nicer than a quick jerky stop, cars are carefully designed to crumple - when they crash
就像缓慢刹车比急刹车要好得多，汽车被精心设计成碰撞时会皱缩变形的样子，
-in a way that lengthens the duration of the impact so that stopping requires less intense acceleration.
这样一来，碰撞的时间延长了，加速度也就降低了。
Lots of acceleration over a very short time is not good for soft human brains and organs.
毕竟短时间内体验极高的加速度，对柔软的人类大脑以及其他器官都不好。
However, people don’t like driving cars with Pinocchio-length noses,
然而，人们并不喜欢开带着匹诺曹长鼻子一般的汽车，
so most cars only have around 50 cm of crushable space in which to dissipate the energy equivalent of our falling stegosaur.
所以大多数汽车只有约50厘米长的可变形长度，来承受相当于坠落剑龙的能量。
That means that, while crumpling, they need to maintain a resistive force of about a quarter the thrust of the space shuttle main engine.
这意味着，当遭受挤压时，这段车体需要抵抗相当于航天飞机主引擎四分之一推力大小的阻力。
Over half of the controlled-crumpling work is done by a pair of steel rails connecting the front bumper to the body,
超过一半的抵挡变形工作是由连接前保险杠和车身的一对钢轨完成的，
which bend and deform to absorb energy and slow the car.
它们会扭曲变形，吸收能量，让车减速。
Most and in ideal circumstances, all of the rest of the energy is absorbed by the deformation of other pieces of structural metal throughout the front of the car.
大多数以及理想情况下，所有剩下的能量都会被车身前端的其他金属部件吸收。
This meticulously engineered destruction allows a crashing car to decelerate at a high but reasonable and constant rate:
这种精心设计的毁坏过程，可以让一辆撞车的汽车以一个高但合理恒定速度减速:
just slightly over the acceleration experienced by fighter pilots or astronauts in centrifuge training.
仅仅略高于战斗机飞行员或宇航员在离心机训练中所经历的加速度。
As comparison, if cars were super rigid (like they were before the 1950s) and didn’t crumple,
相较之下，如果汽车非常坚固(就像20世纪50年代之前那样)而且不会变形，
they would stop so fast that they would undergo acceleration 15 times what fighter pilots experience in training,
他们会非常迅速地停下，加速速度是战斗机飞行员训练时的15倍，
which is definately not good for your internal organs.
这当然对你的内脏不好。
Thankfully engineers have learned to make cars with crunchy crumple zones surrounding their rigid safety cell,
谢天谢地，工程师们研究出了可皱缩区域环绕坚固驾驶室的结构，
because fully rigid cars are not good for fighter pilots or anyone else.
因为整体坚硬的车对战斗机飞行员或是任何其他人都不好。
Except, maybe, robots.
或许，除了机器人。
