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New Speed Record Set For Wind-Powered Vehicles
Hugh Pickens writes "Richard Jenkins reached 126.1mph in his Greenbird car on the dry plains of Ivanpah Lake in Nevada, setting a new world land speed record for a wind-powered vehicle. 'It's great; it's one of those things that you spend so long trying to do and when it actually happens, it's almost too easy,' says Jenkins. The Greenbird is a carbon fiber composite vehicle that uses wind (and nothing else) for power. The designers describe it as a 'very high performance sailboat,' but one that uses a solid wing, rather than a sail, to generate movement. Due to the shape of the craft, especially at such high speeds, the wings also provide lift; a useful trait for an aircraft, but very hazardous for a car. To compensate for this, the designers have added small wings to 'stick' the car to the ground, in the same way Formula 1 cars do. 'Greenbird weighs 600kg when it's standing still,' says Jenkins. 'But at speed, the effect of the wings make her weigh just over a ton.' Jenkins has also built a wind-powered craft that travels on ice, rather than land. 'Now that we've broken the record, I'm going back on to the ice craft. There's still some debate as to whether traveling on ice or land will be faster.'"
Wait, so what's a megagram? Or is that 1024kg?
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
Their usage is dead wrong. Weight is the effect of gravity on mass. The vehicle doesn't "weigh" more at speed - the effect of gravity on it hasn't changed. It just generates a down-force from the wing. To say that it weighs more is about as accurate as saying your weight changes as you jump up and down on a scale, or that an airplane weighs less than nothing when it's flying.
Since energy can be converted to mass, they would have to be going at a large percentage of c to actually "weigh" more.
Not quite. The downward force when it is stationary is 600gN, the downward force when it is moving is 1000gN. The downward force due to gravity, also known as the weight, in both cases is 600gN. The mass in both cases is 600Kg. Neither the weight, not the mass, change. The mass could only change as a result of things being added to or removed from the vehicle, or as the result of relativistic effects (which are present at the recorded speed, but not significant enough to be measured). The weight could change if the mass changed, or if the vehicle climbed far enough from the centre of the Earth for the inverse-square attraction to be reduced (again, this is unlikely to happen unless it raced up a steep mountain; g varies a bit, but not enough to be worth bothering about, over the surface of the Earth). The downward force can change for a wide variety of reasons, but in this case due to a pressure differential caused by air moving more quickly over the underside of the stabilisers.
Note: In this post, g is used as little-g, the acceleration due to gravity on the surface of Earth, while g is the SI unit gram. This is not quite standard notation; they should both be represented by the same symbol, which is just plain confusing.
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Yeah, well I hate breaking out the calculator (or worse, actually reading TFA) to convert 126.1 mph to something non-archaic. (202.9 km/h)
From wikipedia: "The name statute mile originates from a statute of the Parliament of England in 1592 during the reign of Elizabeth I. This defined the statute mile as 5,280 ft or 1,760 yards; or 63,360 inches. Both statute and international miles are divided into eight furlongs. In turn a furlong is ten chains; a chain is 22 yards and a yard is three feet, making up 5,280 ft."
Seriously, WTF?
It's probably for dividing up plots and things. It's nice to be able to evenly divide things into other things. Without the "funny measurements" you end up with lots of fractions, which were much less easy to deal with in the days when a calculator was a person, and most normal people were lucky if they could read.
Note also that an acre is 10 square chains, and 10 acres is a square furlong.
What is a mile? It's a least-common-multiple(ish) of several smaller measurements which happens to be a convenient size for people traveling on foot. The km is also a convenient size for foot travel, but you can only divide it by 2s and 5s without resorting to fractions.
Can you be Even More Awesome?!
The physics that allows one to sail faster than the wind aren't completely obvious. Terence Tao wrote a very good explanation of the basics http://terrytao.wordpress.com/2009/03/23/sailing-into-the-wind-or-faster-than-the-wind/ where he also shows a nice theoretical construction that allows one to accelerate to any speedy (assuming that the universe is Newtonian).
Did they take the average of two timed runs in opposite directions in order to compensate for, you know... wind speed?
Set your phasers on "funky"!