A MYSTERY FOR THE BIRDS SOLVED It is a head-scratching riddle which has troubled scientists and amateurs alike for generations: would a lorry carrying birds weigh less if they were all flying? It may be natural to assume that because the birds are suspended in mid-air their weight no longer has any impact on the lorry. Yet physicists have always maintained that the downward thrust of beating wings needed to keep the birds in the air exactly cancels out the missing load and so the lorry’s weight would not change. Now, for the first time Stanford University has tested the theory by measuring the forces of a bird in mid-flight. And they found that the lorry’s weight would change. It is all down to what happens when a bird beats its wings. The researchers discovered that during the downstroke the bird uses double the force needed to lift its weight so that it can stay suspended during the upstroke. telegraph.co.uk/news/uknews/11345183/Birds-in-a-lorry-riddle-finally-solved-by-Stanford-University.html
Posted on: Thu, 22 Jan 2015 10:00:51 +0000
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