Animal speed ...

50 kilometres per hour (30 miles per hour) is considered to be the limit of the natural human body. Michael Johnson and Donovan Bailey hit top speeds of as much as 43 kilometres per hour (27 miles per hour), but only very briefly. A dog or a cheetah can do far better, yet with the same basic bones, muscles and tendons. The reason for the differences is not fully understood.

Four-footed creatures are not inherently faster. All human runners move their legs at about the same rate. The key how much force they are able to exert on the ground. John Hutchinson, a researcher at the University of London's Royal Veterinary College, has used theory to estimate the top speeds of various animals, including dinosaurs. He came to the conclusion that Tyrannosaurus Rex was a relative slowpoke, only managing 15 to 40 kilometres per hour (10 to 25 miles per hour).

A fast animal, according to Hutchinson, exerts a force of about 2.5 times its body weight on its limbs. The fastest human sprinters have trained to the extent they can exert a force of about four times their body weight. Hence Hutchinson doesn't believe there is a possibility of more than a 5% increase in top speed from current levels. Of course, drugs and genetic engineering could change all that!

By the way, Cicindela hudsoni, an Australian tiger beetle, can run at 2.5 metres per second (5.6 miles per hour) - the fastest ground running insect. Consider that a male athlete is about 1.83 meters (6 feet) tall, his 10.35 meters per second equals 5.6 body lengths per second. Cicindela hudsoni, which is 20 millimetres long and can run 2.5 meters per second. This translates into a relative speed of 125 body lengths per second. Michael Johnson would have to run a 200 metre race in 0.87 seconds to equal the relative quickness of the tiger beetle. So which is the more impressive - man or beetle?

In vehicles - land speed records

Date Driver Vehicle Speed over
1 km		 Speed over
1 mile
km/h mph km/h mph
October 4, 1983 Richard Noble, UK Thrust2 (Turbojet)
n/a
1019.47
633.468
September 25, 1997 Andy Green, UK ThrustSSC (Turbofan)
1148.26
713.496
1149.30
714.144
October 15, 1997 Andy Green, UK

ThrustSSC (Turbofan)
First supersonic record (Mach 1.016)
1223.65
760.343
1227.99
763.035

Air speed records

Class Record Setter

Speed
km/h

 Speed
mph		 Speed
Mach*		 Notes
Insect (level flight)
Australian dragonfly, Austrophlebia costalis
 58 36 Estimate due to it is difficulty of measuring the speed of a flying insect. Investigators have claimed to have measured the tabanid fly at 145 km/h (90 mph).
Bird (level flight)
Red-Breasted Merganser
129 80 Diving duck.  spine-tailed swift
Bird (dive)
Peregrine Falcon
349
217 In a 45° dive. Different sources claim the fastest is the swift, the peregrine falcon, or the frigate bird.
Biplane
Fiat CR42B
520 323 1941
Turboprop-Powered Aircraft
Tupolev Tu-114
876.47 545.07 9 April 1960
Jet-Powered Aircraft
Lockheed SR-71A
3,327
 2,193 Mach 3.3 28 July 1976
Rocket-Powered Aircraft
North American X-15A-2
7,274
 4,520 Mach 6.72 3 October 1967
Winged Vehicle
Space Shuttle Columbia
~ 27,340
~ 17,000 Mach 25 14 April 1981 on re-entry
Manned Vehicle
Apollo 10 capsule
~39,885
~ 24,790 Mach 36 26 May 1969 on re-entry
Interplanetary Vehicle
Voyager 1
62,070 ~ 38,600 launched 5 September 1977
Manmade Object
Helios 2
~241,350 ~ 150,000 17 April 1976

* Mach  1 = 1 x the speed of sound

. 1. Which of these do you find the most impressive? Why?
A tiny little dragonfly belting around at 58 km/h, a bird in a phenomenal dive, or aircraft using engines and fuel? A human, cheetah or tiger beetle? Or maybe something else? Go researching - there are lots of great feats of speed out there.

The Big Winner - Light

So how fast can we go? The problem with travelling at very large speeds is not the speed but getting there. It's the acceleration. To accelerate a human to the enormous speed of light would take unbelievable amounts of energy. Even harder to deal with would be the acceleration needed to get to those incredible speeds - more than the human body can tolerate. Unless you accelerate your poor space traveller for years and years! Lots of ideas and figures to play with, should you be so inclined.

The speed of light, represented by the letter c, is exactly 299,792,458 metres per second or 1,079,252,848.8 kilometres per hour. In imperial units, it is approximately 186,282.397 miles per second, or 670,616,629.384 miles per hour. All electromagnetic radiation, including visible light moves at a constant speed in a vacuum - the speed of light.



Identical twins on Earth.

The speed of light has several properties which may seem really weird:

* Nothing can travel faster than the speed of light.

* No matter how fast you are moving the speed of light seems to be the same speed as if you were stationary.

* As an object or person is accelerated toward the speed of light, time slows down for the high speed traveller. When he or she returns to Earth and decelerates to normal speeds, he or she will be younger than his or her "twin" - someone of the identical age when the trip started, for whom time progressed at the normal pace.



The Earth bound twin ages while the almost light-speed twin doesn't.
What would it be like to travel close to the speed of light and return to Earth 100 years in the future?
You would be no older, but everyone else would have progressed a hundred years. Can you imagine what that would be like? Think how that would have been for someone who left 100 years ago and returned now.

According to the laws of physics, you cannot travel into the past. You can travel to the future, in a way - but only because time slows down for you while it moves on for everyone else. You can't then come back to the present. Playing with the concept of time is a favourite of Science Fiction writers. Play away!