Speed

Speed

Introduction What is speed? Speed is the time it takes to go a certain distance. For most things, speed is measured in kilometers or miles per hour. For example, a speed of 16 kilometers (10 mi) per hour means that something is moving fast enough to travel 16 kilometers in one hour. This speed is recorded as 16 kph (10 mph). Speed can also be measured in other units of time and distance. It can be measured in meters per second or meters per minute. It can be measured in centimeters or inches per second, minute, or hour.

Faster objects are usually measured in larger units of distance and shorter units of time. Slower things, on the other hand, are usually measured in smaller units of distance and larger units of time. For example, a snail's speed might be measured in centimeters per hour. The movement of a glacier might be measured in meters per month. Light-the fastest thing in the universe--moves at 299, 338 kilometers per second (186, 000 mps).

People have always seemed to be fascinated by speed. We seem to love things that move fast. It doesn't matter if it is a cheetah chasing a gazelle, a horse galloping around a track, or human runners dashing toward a finish line. We simply think that fast things are cool. Perhaps that is why some of the most popular Olympic events, from the first games on, have been contests involving speed.

Who Is Fastest? When we watch a track meet or other sporting event, we cheer for the fastest runners. But compared with other living things, humans are not all that fast. In fact, the fastest humans run at speeds of only about 35. 4 kilometers per hour (22 mph).

Speed is important for the survival of most living things. The cheetah, which runs at speeds of up to 113 kilometers per hour (70 mph), is the fastest living thing on land. The cheetah depends on its speed to capture food. For many animals, survival often depends on being faster than the animal that is chasing you.