Reinventing the Wheel  

Oleh:

[s.n]

Jenis: Article from Bulletin/Magazine
Dalam koleksi: The Economist (http://search.proquest.com/) vol. 401 no. 8762 (Dec. 2011), page 20-21.
Topik: Research & Development--R&D; Automobile Industry; Kinetics; Alternative Energy
Fulltext: Reinventing the Wheel.pdf (26.53KB)

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Perpustakaan Pusat (Semanggi) Nomor Panggil: EE29.69 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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For nearly as long as man has used wheels to turn all sorts of energy efficiently into motion, he has been performing the reverse trick with flywheels. From spindle whorls to steam engines, they have served to harvest and store energy for use in the (immediate) future. Now, they are gearing up to energise hybrid cars. The physics of a flywheel is pretty basic. Take a disk that is free to rotate. Apply torque and it spins, gaining momentum in the process. Once the initial torque is taken away, the wheel will keep going. Some momentum is subsequently lost to friction on the bearings and to air resistance. Whatever remains can be put to work, powering whatever gubbins is connected to it. There have been attempts to use flywheels on big buses and trucks, but most involved devices which were only slightly less cumbersome. In smaller cars the extra weight negated any fuel-efficiency savings they might have brought. That, though, is finally beginning to change. One reason is that modern flywheels are increasingly being made of carbon fibre, a material much stronger than steel. This lets them whirr at over 60,000rpm without falling apart.

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