Take a moment and think of something that is fast.
What is the first thing that came to your mind? Did you picture a cheetah, the fastest land animal
in the world, which can run at speeds of 80 miles an hour? Or maybe you thought of the majestic
peregrine falcon, the fastest flying animal which can travel 200 miles an hour when diving through
the skies. Perhaps your mind went in a more mechanical direction and imagined a shiny race car
that can accelerate from zero to 60 miles per hour in a mere three seconds. Or maybe you thought of a
sleek fighter jet which can fly the 2300 miles between Los Angeles and Washington DC in just
over one hour. Whether performed by animal or machine, speed is fascinating, and our fascination
with this simple but powerful law of motion has given rise to many types of competitions.
In every country, on every continent, elite athletes train in swimming pools,
on race tracks, or on ski slopes to race and beat previous speed records. You may be wondering:
what is the fastest thing in our universe? Well, the answer may surprise you. People,
animals, and objects are not the only things that move and travel. Sound also travels.
Have you ever shouted your name in a canyon and heard it echo back to you?
You can hear that echo because of sound waves. They travel out of your mouth and into the canyon.
When the sound waves hit the canyon wall, the sound bounces and travels back to your ears.
Just how fast does sound travel? Is it faster than a cheetah, a race car, or a fighter jet?
Sound can travel as fast as 1100 feet per second, which is about 761 miles per hour.
That's definitely faster than any animal, and for a long time, it was faster than anything
humans could create, too. That is until October 17, 1947, when U.S. Air Force Captain Chuck Yeager
broke the sound barrier, meaning the jet he flew went faster than the speed of sound. Now, almost
100 years later after that milestone, race cars and jets are being developed that are able to go
much faster than sound can travel. Although sound can travel almost quicker than we can comprehend,
there is something even faster. The fastest traveler that we know of is
light. Nothing man has created, driven, or flown can reach or compare to the speed of light.
Light travels at an amazing 186,282 miles per second. To put that in perspective,
consider this. The sun is more than 92 million miles away from us, but it only takes light
from the sun eight minutes and 20 seconds to reach us here on earth. To put it another way,
if you were able to travel at the speed of light, you could go around the Earth seven and a half
times in a single second. Now that's fast! Galileo Galilei is believed to be the first person
to try to measure the speed of light. He was an Italian astronomer and physicist who died in 1642,
the same year Isaac Newton was born. Galileo conducted an experiment in which he stood on a
hilltop with a covered lantern and an assistant stood on another hilltop with another lantern.
Repeatedly, Galileo uncovered his lantern, and as soon as his assistant saw the light he uncovered
his own lantern. Using his own heartbeat and the known distance between the hills,
Galileo tried to calculate the speed of light. Eventually, he was forced to conclude correctly
that the speed of light was too fast to be measured by this method. However,
Isaac Newton used Galileo's calculation for speed in his own scientific work on the Laws of Motion.
Whether we are flying in an airplane at 500 miles an hour, watching an athlete set a new
world record, or racing our friends to the park, speed adds an element of excitement and adventure
to our lives. In the history of mankind, our speed capability has progressed from running
to riding to driving to flying to breaking the sound barrier. Who knows what speed record
we will conquer next with a little bit of hard work, courage, and ingenuity.