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Questão 11 de 25

Exercícios de Relative

Listagem de exercícios

ESPM 2015

The trouble with trying to make trains go faster

By Katia Moskvitch  

    As technology advances, transport gets ever faster, and trains are no exception. But with great speed come great drawbacks. Katia Moskvitch reports on the pitfalls facing train designers trying to reach even greater speed on rails.
    Since George Stephenson’s Rocket, designers have been trying to make trains go faster and faster. Despite all the innovations, particularly in the last 50 years it’s still a dream that all cities around the world could be connected by high-speed trains that complete journeys in a flash, allowing you to arrive at your destination relaxed and untroubled. Why is this the case?
    Going fast on rails brings its own special set of problems. Human bodies are simply not built for rapid acceleration, we experience certain low frequency motions that create discomfort – a feeling of “motion sickness”. We also experience rapid acceleration, for example, each time we take off and land in a plane.
    Then there is the logistics of trying to send a train faster along a track. Going fast means pushing air out of the way, which also requires a lot of power. A train travelling at 300mph (480 km/h) uses roughly 27 times more power than one travelling at 100mph (160 km/h). And at ground level the air is a lot denser than it is at 35,000ft (10,600m) where airliners regularly cruise. That means more resistance, and therefore more vibrations.
    If trains could travel just in straight lines and without any dips, then high speeds would not be a big issue. It’s the bends and the ups and downs that create a problem, especially in Europe, with its many rivers and mountains and old train lines following long-travelled routes.

14 August 2014 | www.bbc.co.uk


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