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Gasoline has approximately 56 Megajoules of chemical energy per liter,
每升汽油约有56兆焦耳的化学能，
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.
多于引爆TNT所产生的能量，也足以给烤面包机提供一整天的能量。
Cars work by burning gasoline to convert that chemical energy into the kinetic energy of motion of the car,
汽车的工作原理是通过燃烧汽油，将化学能转化为汽车的动能，
though almost 80% of it is lost as heat in the engine. Still, 20% of 56 million joules is a lot of joules…
尽管其中80%的能量在发动机中以热能的形式损失掉。但5600万焦耳的20%也是很多的......
To give a direct sense of gas-to-car conversion, it takes about five teaspoons of gas to accelerate a 2 ton car to 60kph,
为了直观感受汽油与汽车之间的能量转换：一辆两顿重的车加速到每小时60公里需要约5茶匙汽油，
and about a third of a cup more for every additional minute you want to keep it going at that speed.
如果你想让它继续以这个速度行驶，那么每多一分钟还另需三分之一杯的汽油。
That might not sound like a lot of fuel, but the energy of a car moving 60kph is equivalent to dropping an elephant –
听起来好像不多，但一辆以每小时60公里的速度行驶的汽车的能量相当于扔下一头大象——
or stegosaurus – from the top of a three-story building. And in order for the car to stop, all that energy has to go somewhere.
或一头剑龙——从三层楼的高度往下扔。为了停车，所有的能量都必须集中到某个地方。
If the brakes do the stopping, they dissipate the energy by heating up.
如果踩刹车，它们会通过加热来消耗能量。
Or in the case of a collision, energy is dissipated by the bending and crumpling of metal in the outer areas of the car.
或者在撞车的情况下，能量会通过汽车外部区域的金属弯曲和扭曲而耗散。
And just like how smooth braking is nicer than a quick jerky stop, cars are carefully designed to crumple - when they crash -
就像是平稳刹车比急刹车更好一样，汽车经过精心设计成可以扭曲，在碰撞时，
in a way that lengthens the duration of the impact so that stopping requires less intense acceleration.
就能延长撞击的持续时间，这样停车时就不需要太大的加速度。
Lots of acceleration over a very short time is not good for soft human brains and organs.
短时间内的多次加速对人类脆弱的大脑和器官都不好。
However, people don't like driving cars with Pinocchio-length noses,
但大家都不喜欢开和木偶鼻子一样长的车，
so most cars only have around 50cm of crushable space in which to dissipate the energy equivalent of our falling stegosaur.
所以大多数汽车只有大约50厘米的可压碎空间来消耗相当于下坠剑龙的能量。
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，在受挤压时，它们需要保持一个相当于航天飞机主引擎四分之一推力的阻力。
Over half of the controlled-crumpling work is done by a pair of steel rails connecting the front bumper to the body,
超过一半的控压工作都由一对连接前保险杠和车身的钢轨完成的，
which bend and deform to absorb energy and slow the car.
钢轨弯曲变形以吸收能量并降低车速。
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.
大多数情况下，在理想的情况下，所有剩余的能量都被车身前部其他结构金属的变形吸收了。
This meticulously engineered destruction allows a crashing car to decelerate at a high but reasonable and constant rate:
这种精心设计的破坏可以让一辆撞毁的汽车以一个高但合理且恒定的速度减速：
just slightly over the acceleration experienced by fighter pilots or astronauts in centrifuge training.
只是略高于战斗机飞行员或宇航员在离心机训练中体验到的加速度。
As comparison, if cars were super rigid (like they were before the 1950s) and didn't crumple,
相比之下，如果汽车超级坚硬（就像它们在20世纪50年代之前那样）且不易弯曲，
they would stop so fast that they would undergo acceleration 15 times what fighter pilots experience in training,
那么它们停车速度就会非常快，以至于它们将承受的加速度是战斗机飞行员训练时的15倍，
which is definitely not good for your internal organs.
这绝对不利于你的内脏器官。
Thankfully engineers have learned to make cars with crunchy crumple zones surrounding a rigid safety cell,
幸运的是，工程师们已经学会了在坚硬的安全电池周围制造出带有撞击缓冲区的汽车，
because fully rigid cars are not good for fighter pilots or anyone else. Except, maybe, robots.
因为硬式汽车对战斗机飞行员或其他任何人都不好。或许机器人除外。
This MinutePhysics video was made possible by Ford - I was able to talk to an awesome crash test safety engineer there
本期视频由福特汽车赞助播出—我在那里和一个很棒的碰撞测试安全工程师谈了谈
who told me all about the complex physics and engineering that goes into vehicle development and improving how cars perform in a crash.
他跟我讲了所有关于汽车开发和改善汽车在碰撞中的表现的复杂物理和工程问题。
Ford gave me this opportunity because they want you to know how important and carefully designed all the parts involved are,
福特给了我这次机会，因为他们希望大家了所有部件的重要性以及这些部件是如何经过解精心设计的，
and in particular that the only parts developed and tested to work with their vehicles are original Ford parts.
尤其是，只有那些用于开发和测试车辆的零部件才是Ford原产的。
If you want to learn more about why the right parts matter, you can head to takeagoodlook.com.
如果你想了解为什么合适的零件很重要，你可以访问takeagoodlook.com。
And I personally want to say that making this video has just reinforced to me that regardless of what kind of car you have,
就我个人而言，我想告诉大家，制作这期视频让我坚信，不论你开的是哪款车
big dents and deformations in the body aren't just aesthetic problems – they can be safety hazards, too.
车身的大凹痕和变形不仅仅是审美问题——它们也可能是安全隐患。
