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It’s your world: Speed limits

It is not commonly known that a particular running bird would cause a considerable stir if allowed to enter the Olympics.

Bob Harrington

Arrow Lakes News

This is the age of rapid travel. Certainly more people are getting nowhere at a faster rate than at any other time in history.  At any rate, speed being a topic of considerable concern, it might be interesting to look at some of the speedy neighbours who inhabit spaceship Earth with us.

The bird world boasts of a number of rapid flyers, but it is not commonly known that a particular running bird would cause a considerable stir if allowed to enter the Olympics. The heavyweight Ostrich, all 136 kilograms of it can lope along at a speed of about 56 kilometres an hour. The ostrich is the largest living bird in the world today.

The smallest bird, the hummingbird, some of which weight less than a penny, qualifies as a living furnace.  If a 77 kilogram man expended energy proportionately to the energy used by one of these living jewels he would have to consume about 285 pounds (130 kilograms) of meat per day.  It has been calculated that a hovering hummingbird uses energy at such a rate that this 77 kilogram  man would have to evaporate 45.4 kilograms of perspiration per hour just to keep his skin temperature below the boiling point of water. If you have watched hummingbirds hover over a flower, they probably aren’t traveling between plants at much more than 40 kilometres per hour, but the blur of the wings while hovering affords ample evidence of the energy expenditure.

Various other birds also maintain respectable speeds.  Some ducks and geese fly at 64 to 96 kilometres per hour in calm air; pheasants move at 55 to 61 kilometres per hour; and the ungainly appearing curlew will clock in at 64 to 80 kilometres per hour. The North American duck hawk, or peregrine falcon, is reputed to exceed 320 kilometres per hour in a power dive.

Mammals aren’t so slow either! The cheetah, a member of the cat family, has been clocked at 640 metres in 20 seconds. This figures out to be just over 113 km. per hour. True up to a few years ago and probably still true, is the fact that no racing car could match the acceleration of the cheetah which moves from a standing start to 72 kilometres per hour in two seconds. The African wildebeest, the springbok and various gazelles can do 80 kilometres per hour. The two ton cape Buffalo can charge at about 56 kilometres per hour, and if an elephant doesn’t care for you, he might attack at a rate of about 32 kilometres per hour.  Grizzlies don’t have to apologize for their speed as an enraged grizzly can turn out at nearly 48 kilometres. per hour, and can sustain their speed long enough to be a Stanley Cup shoo-in.

In the land down under, the kangaroo, when in a hurry, resorts to a gait that becomes a series of leaps with the tail acting as a counter-balance.  They can travel at a steady 32 kilometres per hour and leap about 48 kilometres in about 30 seconds for short bursts.  The individual leaps may be about five times the length of the animal’s body — or about 7.6 metres.

Among insects, grasshoppers fly at about 24 kilometres per hour and sphinx moths attain 49 kilometres per hour. Author S.W. Frost in his Insect Life and Insect Natural History says, “The most remarkable speed is exhibited by the male of the deer botfly, which according to some authorities has a velocity of 818 miles per hour.” Some physicists believe such a speed impossible and that an insect traveling at such a rate would be crushed. I can’t vouch for this one, but I do remember reading one time that according to the laws of physics, a bumblebee should not be able to fly because it is aerodynamically unstable. Well, it’s nice to know that some things still baffle us. It would be boring if we knew all the answers.

One of the interesting things about speed is the fact that an organism is adapted to its natural speed limits and can make out quite well as long as it stays within them. This is why people who walk rarely go into the ditch!

Cheer up though! To appreciate speed properly remember that when a wonderful light gleams in someone’s eyes just for you, that reflected light itself travels in excess of 297,600 kilometres per second. How’s that for a quick ending?