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This is Scientific American's 60-second Science, I'm Christopher Intagliata.

这里是科学美国人——60秒科学系列，我是克里斯托弗·因塔格里塔。

When you walk with a backpack, you know how the stuff inside sways from side to side? Nowscientists have figured out how to tap into that motion to generate electricity.

当你背着背包走路时，你知道包里的东西是如何左右摇晃的吗？现在科学家已经知道如何利用这种运动来发电。

Here's how it works. Picture a pendulum¹ mounted to a backpack frame and stabilized² withsprings on either side. The pack's weight is attached to the pendulum, so the pendulumswings side to side as you walk. Gears then use that swinging motion to drive a generator³, andthe generator spits out electrical current to charge a battery.

下面来解释其工作原理。想象一个钟摆被装在背包框架上，然后用框架两边的弹簧固定。背包的重量与钟摆相连，因此你走路时钟摆会左右摆动。之后，齿轮会用这种摆动来驱动发电机，而发动机会吐出电流为电池充电。

Volunteers carried the pack while walking on a treadmill⁴ and wore masks to measure the flowof oxygen and carbon dioxide. Walking with the slightly swaying 20-pound load, the device didnot significantly affect the volunteers' metabolic⁵ rate compared to when they carried thesame weight fixed⁶ in place. In fact, the energy-harvesting pack reduced the forces ofacceleration they'd feel in a regular pack, which might mean greater comfort for a long hike. And the device did produce a steady trickle⁷ of electricity—the operative word being trickle.

志愿者背着背包在跑步机上走路，他们同时戴着口罩测量氧气和二氧化碳的流量。与相同重量的固定负重相比，在轻微晃动的20磅负重下行走时，该设备未对志愿者的新陈代谢率产生显著影响。事实上，收集能量的背包减少了他们在普通背包中感受到的加速力，这可能意味着长距离徒步时背这种背包会更加舒适。这个装置确实产生了稳定的电细流——关键字是细流。

Because if you up the load to 45 pounds, the passive motion of the pack could fully⁸ charge aSamsung Galaxy⁹ S10 smartphone only after 12 hours on the trail. The details are in the journalRoyal Society Open Science.

因为如果把负重加到45磅，那在走路时，背包的被动运动只需12个小时就能给三星Galaxy S10智能手机充满电。研究详情发表在《英国皇家学会·开放科学》期刊上。

But here's the rucksack rub: the energy-harvesting device currently weighs five pounds. Theresearchers say that's about four pounds too many to be a smart alternative to batteries. Sothey hope that more research lets them lighten the load, to ensure the pack charges you upwithout weighing you down.

但现在有个背包困难：目前收集能量的设备重达5磅。研究人员表示，这个多出约4磅的设备不能作为电池的智能替代品。因此，他们希望，更多的研究能让他们减轻这一负担，确保背包在不让你感到沉重负担的情况下为你充电。

Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.

谢谢大家收听科学美国人——60秒科学。我是克里斯托弗·因塔利亚塔。